id say rotaries are very reliable, but there not very durable.
they wont suffer abuse (no oil, boost spikes, detonation) but if you look after your car it will last well.
i own a rotary and the only stuff i have had to fix on it has been diff and gearbox mounts, and the clutch.
if your going to buy one do proper research, dont just listen to what everyone on toymods (or ausrotary) thinks.
the plus side of rotarys is the dont weight much, you can make ALOT of power for comparativly little $$$, and they love to be hammered all day every day.