This is a very faithful port, I've had it for a few weeks now and beaten the starter scenarios on both my iPhone and iPad. Larger screens are ideal, but it works just fine on my phone's 4.7" screen.
Ever since the terrible free to play RCT 4 came out, I've been hoping they could just give us the game we love. The port is perfect and the dev team is very active.
For an extra $6 you can get the toolkit that lets you freely create rides, scenarios, and also export and import saves for others to use. As an added bonus, the saves are cross compatible with RCT2 on PC.