Jak and Daxter: The Precursor Legacy was a bright, colourful platformer with a limited storyline and a large focus on collecting and exploring. Jak 2 was a firearms-heavy story-based GTA clone set in a grim location called Haven City. Why did Naughty Dog decide to change the series' direction so drastically, what were the main alterations, and did it pay off for a better sequel?
In my opinion, Jak 2 greatly improved on the narrative, as Jak 1's plotline was very basic and loose and simply served as a reason for the heroes to start exploring the colourful world. Jak 2 changed this to a very story-driven experience that still feels like true Jak and Daxter, as the cut scenes and storyline in general employ the same humour and style, which overall refines the Jak and Daxter experience. This as well as its greater array of characters such as Vin, Krew, and Torn add to the experience much more than the unimportant characters of the original (it's too bad Samos and Keira seemed to get short shrift in the sequels). This was certainly an improvement.
Hub: Jak 1's hub was amazing: a truly massive sprawling open world with seamless integration with each other and bursting with colours, variety and unique enemies and environments. Jak 2 on the other hand features a mostly unoriginal gritty city setting with bland, boring Metal Head and Hellcat enemies with only occasional areas that differ from this. Definitely a step down from the first game.
Jak 1 was light, carefree, and appropriate for even the youngest of players (ignoring the revealing outfits of Keira and Maia perhaps) whereas Jak 2 involves death, guns, swearing, and Daxter staring at breasts. While they managed to include all this and somehow still retain the original Jak style, this is likely to be alienating to younger players. While it seems quite unnecessary in my opinion, I also believe they pulled it off successfully enough.
As a side note, the removal of the different eco powers in favour of shooting elements makes the game seem less like a Jak game and more like the Jak characters shoved into a shooter game.
In conclusion: Jak 2 was a worthy sequel that kept things interesting and unique when they could easily have gone with the repetitive cash-grab sequel, but it can never match up the magic and quality of the original.