It's like a mixing of Mario 64, and Crash Bandicoot that comes out as quite the nice little package.
While the story may not be much, at least it does have one. It gives you a pretty good idea what you have to do as you travel from area to area collecting Power cells which allow you to advance through the game. In total there are 101 Power cells to collect, but it's not necessary to collect all 101. It's possible to finish the game with around 72 of these egg shaped power cells. But collecting all of them treats you to a bit of an extended ending.
Jak can attack enemies by punching them, or do a spinning attack. But he can also perform uppercuts, and butt-stomps. You can also collect some Yellow eco which enables you to fire out balls of yellow energy. While it is possible to get through the game simply using the spinning attack, the few other moves available liven up the experience a bit by giving you a few more attacks at your disposal.
Aside from the Yellow eco, there are also Blue, Red, and Green eco. Blue eco simply makes you faster and allows you to pull off move quicker. Red boosts your attack power and allows you to bust open certain chests that you normally could not. Green eco is your health. Jak can take 3 hits of damage before dying; getting more green eco will replenish his health. With all these beneficial eco colors, there is also Dark eco which will pretty much kill you instantly. So it's to be avoided at all costs.
Throughout the game there are various cutscenes that help explain and advance the plot. The voice acting is very well done, and the voices fit their goofy, cartoony character models.
One of the faults major of Jak & Daxter is that the game is very short. You just start to get going and then you're almost done. It's a bit disappointing when you finally find out the bulk of the story, and you're already more than halfway through finishing the game.
Despite its short length, Jak & Daxter is a great first game in the series. It spawned 2 sequels, which is probably the best thing it's done. If the Jak series interests you at all, its definitely worth it to play through the first Jak & Daxter to see how the story, and the characters all began.