Amazing game, fun to play, and some very challenging scenarios.
There are many scenarios with many different objectives and terrain. You can play in a desert, and abandoned pier, some cool mountains, and many other interesting places. There can be objectives like obtain a certain number of guests, cash, park value, park rating, and loan amount. My favourites are Pacific Pyramids, Mel's World, and Evergreem Gardens.
There are many roller coasters, thrill rides, gentle rides, shops & stalls, water rides, and transport rides. You can choose already built designs or your own custom creations, but beware! If your ride is too thrilling, or not enough, guests will not go on it, I have learned that the hard way! Eventually though, you get the hang of how to make killer coasters. Here's a tip, make a Shuttle Loop with a on-ride photo section, and you will make over $10 000 by the end of the scenario, almost every time! It is a steel-roller coaster.
You have to hire park staff such as janitors, security guards, and mechanics. Don't just hire as many as want though, as they can cost a fortune. I recommend keeping a screen of one handyman in the corner of your screen and picking him and dropping him if you see garbage.
Some downsides is you don't have a sandbox mode like in the 3rd game and not even a ride designer, but you can just beat a game, take a huge loan, sell everything, and build it in the park, and save the design. Also, it can be difficult at the beginning if you don't understand basic economics, so it may take awhile for some.
Overall the game is a huge entertainer, and I recommend it to anyone, but try to get it in a cereal box. ;)