There are some notable names running on Joyent's infrastructure. They could have used AWS instead, but they didn't. I don't know if that means anything though, since there are odd ducks in every crowd.

One thing I like about Joyent is they're not trying to solve hard-to-impossible problems like Amazon (e.g. EBS), but rather realistic and immediate problems (e.g. guaranteed disk latency). For all EBS's promises, the latter is vastly more important to me; I've had few problems EBS would solve, and a truckload that higher-quality I/O would.

Also, those analytics are nothing to sneeze at. That's worth almost as much as the IO.

Joyent may be unknown to you, but they do a lot of interesting things with Solaris/Illumos, tons with Node.js, and have been around for quite some time. They were an early host of Twitter and have been around for 7 years at this point.

Keep in mind that EC2 has only been out of beta for 3 years next month.

From all the hosts I have used, Joyent has been the most rock-solid (by far). So personally it rings a bell :)