The traditional,fast style of Sonic's gameplay combines well with some nice looking 3D environments.
You can run at very fast speeds and run fast through the loops(just like in the GENESIS Sonic games,and to see it in 3D looks amazing.
There's also times you'll need to outrun giant boulders or slide across rails very fast,cart sections and you'll need to make use of Sonic's wall jump ability.Of course while you're doing this,enemies will attack you and there's occasional pitfalls and lazer beams and even a section you have to swing to different vines before crocodiles leap from the water and eat you.
The gameplay does have some problems though.The first one I'll mention is it can be difficult to judge distances with rail jumps and you could try to jump on a rail that's right next to you,and miss it and fall to your death.Another problem is the camera angle,and if you try to adjust it sometimes it won't help and won't give you a good view of the jump you need to make and can cause you to fall to your death.Also,if you crash during the cart sections,you'll lose a life,even if Sonic gets up right after it to show he isn't even badly hurt,why do you lose a life for that? Another thing that annoys me about this game is you have to constantly switch between Sonic,Knuckles and Tails to get through different parts of the levels,which takes away the sense of speed.Also,Knuckles is much more useful than Sonic(he can destro enemies much easier than Sonic,and Sonic feels a bit redundant in this game compared to Knuckles with his powerful attacks and Tails who can fly).The wall jumping was a bit difficult too due to the timing and precision required and when you jump from swinging vines,if your timing if a tiny bit off,it can make you lose a life.
After all these complaints,you might be wondering why did I give the gave a 9/10? Well the reason is because the game is still very fun.It has the speed of the GENESIS Sonic games with 3D environments(so you don't always have to travel in a straight line),and when I was in the tropical environments I liked to run off the main path and onto the sand and near the water and it was fun.
The levels do a good job of mixing colorful and high tech levels,and consist of tropical environments,futuristic,casino stage with dazzling lights and the pinball style play,jungle,haunted castle,desert canyons(with beautiful sunset in the background),on an airbase and in a heavily defended fortress with futuristic weapons.Even the lazer weapons shoot a colorful purple or blue beams of light.
The speed of the gameplay can make you react/think very quickly or you will die,but it makes the gameplaye exciting,but requires a bit of trial by error.
There is boss fights against Eggman's machines again,but this time,the machines he uses can be big and look more dangerous,such as giant planes.
There is cinematics which look quite good too.
The music suits the environments well,from the peaceful music in the tropical environment,the electronic/techno style music in the futuristic levels.The electronic music the plays during the fortress level can sound intense and exciting.
The voice acting is a bit too childish.
Overall,it's a great Sonic game with the traditionally fast style of Sonic gameplay combined with nice 3D levels,but a few problems take away some of the fun.