Not great... (Score 3, Interesting)

I have yet to find one that could totally replace my desktop/laptop. Cloud9 and Nitrous are probably the best of the bunch. Both offer a nice IDE and desktop synch. However, you'll always sacrifice speed/performance and ease of use for convenience, even at the highest paid tier of service. When I used Cloud9 and Nitrous they were considerably slower than development on a desktop/laptop. Likewise, things always just seemed more difficult. If I were going to use a cloud IDE again I'd invest in server space at someplace like Digital Ocean and install the open source version of Cloud 9 (or a similar app) on the server to create my own personalized cloud service.