One of the best sonic games
Story: The story is actually good for a sonic game. Some of the characters actually have unique and interesting personalities (like shadow) and the story is slightly darker. In fact the backbone of the Sonic universe comes from Sonic adventure 1 and 2.
Sound: The voice acting is pretty bland. Deem Brist does a great job of Dr. eggman and Ryan Drummond voice goes with Sonic's cool attitude but the others are all average and below. The voice acting is still better than many of the future sonic games and the voices can be changed to Japanese if you still can't bear the English ones.
Music: Most sonic games, even the not so good one do one thing right and that is music. Sonic adventure 2 is no exception of this. The music consists of rock and pop, as well as some jazzy songs and rap (ugh). Not all of it is good, but the majority of it suits the level and some of it is just plain addicting (escape from the city)
Gameplay: The gameplay is seperated into 3 different categories. Racing levels / action stages, shooting levels, and chaos emerald hunting.
Racing/action stages: (sonic and shadow). These levels are by far the best part of the game. You run through these 3d stages at pretty fast speeds avoiding obstacles, until you reach the finish. There is a lot of platforming involved but unlike sonic unleashed, it is not frustrating and feels fun rather than cheap. You can grind on rails, home in on your enemies, bounce on springs, and dash across a path of rings with a push of a button. To me it is the perfect balance of speed vs platforming.
Shooting stages: (Tails and dr eggman) These stages have you control a tails or eggman in a mechanized vehicle as you shoot and platform your way to the finish. You highlight targets with a laser and then shoot missile at the selected targets killing them. You also have the ability to jump and hover over pits, which makes up for a bunch of the platforming. These levels are much less fun, and while they can be exciting at times, some of the later levels seem slightly long with some annoying/difficult platforming sections.
Emerald hunting: These stages have you go around the stage hunting for 3 shards of emeralds. A indicator on the bottom blinks various colors and beeps telling how close you are. These levels can be fairly big, and it can get tedious to try to find 3 small shards in such a large environment. However, doing so does give you a sense of accomplishment.
Bosses are mixed into stages, and range from boring, to decent. The secret final boss is pretty challenging and fun, and you feel a great sense of accomplishment beating him.
Other than the story there is mini kart racing game which is horrible, multiplayer, and virtual pets called chao.
Chao: Chao are a great feature in this game and add a lot of re-playability. Chao are cute creatures that you raise in these gardens that you can interact with. Throughout the actions stages you get chaos drives or animals which you can use to increase chao stats which can then be raced to gain items which they interact with in the garden. You can also use any remaining rings you get at the end of each stage to buy new egg colors, more advance fruit, and other various objects. Aside from that you can name your chao at the fortune telling house, and teach it skills it will randomly perform like (flute) at the school. There are 3 main chao hero, dark, and neutral and each chao has a corresponding garden (2 are locked). There are multiple chao varieties and colors you can make through breeding, skill building, and animals parts which they can wear, and it is a lot of fun.
Re playability:
There are over 100 embalms to collect (180 in the gamecube version) which once all gotten give you a secret level. You get these through various means such as winning chao races, completing other objectives for levels (such as collecting a certain amount of rings) getting an A rank on all missions...
Difference between sonic adventure 2 battle and sonic adventure 2. There are a few differences between the games for those that already own the original. One the graphics are slightly better. The multiplayer has also been expanded with all characters available from the start and more levels. The chao garden black market has also been improved with the addition of colored and shiny colored chao eggs which allow for endless chao combinations and even two toned chao.
To all sonic fans who don't have sonic adventure 2 I highly recommend this game. You will have SO much fun with it. If you have sonic adventure 2 already for dreamcast, there is no need to get this version unless you enjoyed the multiplayer, or enjoy the chao raising.