A game only limited by your imagination. And a few bugs.
The best things about this game are the building capabilities, improved graphics, and fireworks creator.
Graphics: 9/10
Completely better than the pixely isometric junk from Roller Coaster Tycoon 1 and 2, this game is complete with breathtaking 3D graphics and a fully rotatable camera. The people, instead of being a bunch of identical humans, are now unique individuals, each with their own name, clothes, and looks. Some of the scenery is truly beautiful. The only bad part of the graphics are the people. They don't have fingers (just "crab claws") and are very blocky and simple.
Music: 8/10
A large amount of "muzak" is very mellow, and there are a few catchy tunes. Also, you have the ability to import your own music.
Gameplay: 10/10
There is so much to do! I can't even begin to list the ways you can customize your park. It is incredibly fun. I'd have to say that the best part is the sandbox mode, where nothing, not even money, can limit your park. You can build an amusement park EMPIRE. There is so much you can control, everything from coaster speed to trail color to landscape; you can even decide how many pickles you want on your park's burger!
With the Fireworks MixMaster, you can shoot off fireworks to the rhythm of playing music.
Of course, the classic scenario mode is back, but it's not as much fun as sandbox mode.
Functionality (Glitches/bugs): 6/10
A ride that is perfectly working one minute will suddenly explode. A janitor will walk right by a pile of vomit and not pick it up. A guest will jump off a diving board from 500 feet and land on the pavement. Costumers will flood to one of your rides one minute, then suddenly abandon it. Slow load times. And occasionally, an unexplained glitch can cause the game to shut down. At one point in the game, I clicked on a balloon, and the game crashed and quit.
Variety: 10/10
See GAMEPLAY above. ^
Sound: 8/10
Crowds mumble, gears clank, and go-karts vroom.
Overall, this game is loaded with an amazing amount of content. Unfortunately, a number of bugs keep this game for earning a perfect 10. However, this is a great game that I highly recommend you get.