Firstly I want to cover the topic all younger Star Wars fans seem to not understand, pretty much mostly those who weren't around for the Original Trilogies, and while I myself wasn't as I am only 18, I have built this out of hearing from those who were around for it and my own experiences seeing them in order of release at a young age. Why is Boba Fett such a cool character? This will be a lengthy explanation so if you just want to hear about the movie ideas feel free to skip to "BOBA FETT: THE MOVIE".
WHY WE LOVE BOBA FETT
Many people credit his armor, and while this has a partial truth to it, its only a small part of the entirety. (Minor spoilers for anyone who hasn't watched the original series... and for you few who are on here and apply to this... for shame, for shame.)
Origins: Most of you believe he started in Episode V, but he first made an appearance before that as the main antagonist of the short cartoon of the infamous Star Wars Holiday Special introduced as "Vader's right hand man." He was mysterious, he outsmarted the protagonists, and being a bounty hunter he had no true allegiance with no remorse and little emotion without any Empire or Alliance to rely on, just himself. He was hyped up as a major villain for Episode V while the movie was in the works and the primary threat.
Episode V, the main source: For this much was the same as with Holiday Special, at the end of the movie he was again teased to be a main antagonist and not too much is shown of him. What is shown is that he's efficient, he knows what he's doing and instantly tracks down the tricky and lucky Han Solo who is never again outsmarted throughout the entire Trilogy, he is shown as being on equal with Vader, talking in a threatening voice to Vader if he doesn't receive his payment, see the video below for original voice. Yes, Boba Fett was directly threatening Vader and the Empire, alone, with the result of getting what he wants, this essentially establishes that he's an extremely valuable military asset to the Empire, to the level of Tarkin himself and is put on equal with Vader through the way they're paired together side by side being the only one to ever be seen this way with Vader and giving Boba such blatant disregard for any threat Vader could have put up.
Episode VI and why it doesn't go against him: We all know the story, Boba falls into the Sarlaac pit and this is commonly used as the greatest reason for why he isn't a good fighter, however, take a closer look at how that scene plays out with me. Boba isn't paying attention to the blind man flailing behind him because if Han had hit anywhere but the small jetpack controls, Boba would have stood his ground and been able to get a clean shot that would have decapitated Luke, he was aiming for the biggest threat. Then there's also the fact its all for plot convenience as Lucas just wanted to get Boba out of the way so that he could focus on the father-son conflict and not have any other major threats taking away from that as said by George Lucas himself and let's just add that plot armor of Luke.
Expanded Universe: Now this is where the stories of Boba thrived and he finally got that spotlight that had been teased (though apparently completely unintentionally according to George Lucas... he unintentionally creates good characters killed too quick way too much.) throughout his first three appearances, the writers capitalized on his popularity, he has probably stared in more comics then most of the main characters in Star Wars and was shown as a pure professional. He was said to have killed Jedi for a lifetime, he knew how to hide himself from the force, he could draw a blaster the shoot the heart out of someone faster than it could finish a beat, he became Mand'alor, he nearly matches Vader in combat and manages to unite the Mandalorians once again into one of the greatest fighting forces in the Galaxy. He even matched Kenobi in battle at age 13 just a few months after Order 66. In total Boba Fett is something Lucas is good at, accidentally and purposely making fantastic villains that usually don't last long enough in the films so all that build up carries over to outside material where things can get a little insane.
Extra details: Originally Vader was going to be a bounty hunter, the look was finalized and the entire original idea of Vader became Boba Fett. One of the backstories Lucas considered for Boba in the prequels was for him to be the brother of Darth Vader but decided it was "too hokey."
BOBA FETT: THE MOVIE
Now we're on the what Disney must do section.
I'll be the first to say I'm extremely skeptical of anything made Star Wars especially after they discarded LucasArts and killed off 1313, a game very late in development that would have explored the underworld of Star Wars, long anticipated by older Star Wars fans only to be thrown to the curb so EA of all companies would have full rights to the games.
Character: Boba remains Boba
Yes Boba is extremely skilled, able to draw and shoot through the heart of a man before it could even beat, and yes, he has enough gadgets to deal with almost any situation, or enough physical strength to overpower Bossk in pure brute force, or how he climbed up the Millennium Falcon while it was in flight using only his jetpack, or his speed in evading starfighter fire, and so-on and so-forth, however, this is not what makes Boba Fett, well, Boba Fett. No, what makes the man is first and foremost his wit. We also have to keep that Boba is not just evil, to give Boba a comic equivalent think a Batman except with little regard for life, a dark grey morality, and makes his money through spilling blood. He is cold and calculating with little moral obligations but does follow a code and won't take a hit unless he feels its justified, though it doesn't take much to be justified in his book and if you know anything about the target you are just as worthy of his sentence. He also better be officially a Mandalorian and use that original voice or I will be very upset with you Disney, the very little you have done on them has gone very much in the absolute wrong direction completely away from their origins, hell the Mandalorians were based around Boba Fett. Also Boba should have been cold cut off and calculating since the second he lost his father, I don't care what The Clone Wars (2008 version) says, no, that whiny kid is not how Boba is supposed to act. Anyway I'm getting sidetracked, now onto the script.
Plot: dark, Dark, DARK, DARK
This is absolutely and completely necessary, it has to be on the R rated end because, well, flamethrowers and disintegrations melting faces off graphically because this is Boba Fett, we're talking about who will torture a man in public for answers with just his fists, it should definitely get brutal. It must be a mature story, not in terms of gore or intercourse (though it should contain brutal scenes as I said before) but of plot and characters, it should explore the criminal underworld of the galaxy much like 1313 sought to, it can't focus on character development as said before Boba became that character the second he picked up his father's helmet, rather it should focus on the rise of his reputation and his hunts, it could be something like a cinematic version of the game Star Wars: Bounty Hunter but replace Jango with Boba and the scene of the nearing end of the Galactic Republic with early Empire Era, sort of like what 1313 was going to do (I'm upset about it alright? I loved Bounty Hunter and this was its pseudo sequel). If the rumors are true and Lucasfilm is having trouble with getting Boba to be menacing and the hero of the story its really quite a simple answer, he's not the hero but the anti-hero, he does what he feels is the correct path in a slightly twisted view and with immoral tools all while getting paid to do it. Of course this would have to end with a very dramatic scene of Boba climbing out of the Sarlacc, we already know Boba's alive just waiting on a story to pull him out, while it would be obvious it would still dive huge amounts of excitement and nostalgia to the ending as Boba returns to the galaxy for many fans.
That, is what I want from a Boba Fett movie. Disney, Lucasfilm, seriously, don't screw these up or you won't recover the fan base, which includes me. You've already split it hard by changing the Expanded Universe to non-canon, you will forever push away those you split off if you screw these up. This isn't a threat or anything, just an opinion.
I'd love to see your thoughts on this in the comments below.