I've had the game for a year now (Japanese) and let's just call it Ultra Coaster 3D Lite. It looks better than UC3D, and has a lot of the functionality of UC3D, but it has a lot of problems that warrant it inferior to UC3D. Things like, you MUST build the lift directly out of the station for it to work (or the program thinks it's just another hill), you only get 150 pieces to work with in the last scenario (out of 6 scenarios), and your coaster must always fall within 'parameters' which means, it must work, reguardless of how it runs. No real sandbox mode, per se. Let me stress that a 'piece' of track in Jet Dream Coaster (Jap. title) is a two foot section of track that you can bend to your will, not a fixed shape like RCT.
All scenarios must be completed with goals in mind, very much like RCT. But overall presentation is like a cross between UC3D and SimTP. It is an ok game, prettier than UC3D, but no where as in depth.
Now, things between the Japanese release and the US release will change (they already added an online coaster swap feature in the US version), but most of it will be like the above description.
Hope that helped.
Chris