Been with them for 4 years now. Their servers are optimized to work with WordPress (and WPMU if you get a dedicated server), therefore Buddypress is a piece of cake. Their shared servers are really good actually, you get the best plans (seriously the stuff you can do is a lot more than the usual hosting package), and really good prices.
I may experience about 2-3 downtimes a year, which are usually for maintenance, seldom for hardware failure.
Plus, the guys at support really know what they’re doing and they can fix about anything really quickly, or even move you instantly to another server if it’s not working… and you dont have to do anything!