jazz 1 had some goodies that didn't appear in jazz 2 (what were they thinking) like the 3d bonus stages (the idea was a ripoff of sonic games, but way better).

jazz2 is a bit lame because it had only 2 movies!!! the "you beat the game" one was pathetic, the intro one is way better, it doesn't even have movies between the chapters!!!

also jazz2tsf isn't really a game, it is more like a cheap mod or "standalone expansion pack", it is only one huge storyless chapter!! it should had been an expansion pack, an addon. (obiously not allowing the standard stages be played with lori).

jazz2 failed because it was dull, they could have added cool elements like the frog of the shareware episode in the retail version, 3d bonus stages, more movies. i don't say that the stages are bad, what i say is that they use the same elements in all stages, you can get tired of that sometimes.
the stages are beatiful, but it is boring to always end the stages by reaching the finish, it worked in super mario games, but it doesn't work anymore, they didn't really innovate from jazz1, although multiplayer support is great goodie.

my 2c