Mine has had no issues in the 8 months or so I've had it (knocks on wood). The 360 needs very good venting. Nothing stacked on it etc. I would even recommend not running it with a glass enclosure closed.
Determining somethings reliability is iffy. Look at a Tivo or any device with a hard drive. Usually that drive will last at minimum 5 years and inside the Tivo it is running ALL the time. But, there are times when they have died within a year and Tivo only gives you 90 days parts and labor! Out of the 5 million that they have, this happens fairly frequently but then when you look at total cased and compare to boxes under sub, it isn't that great a piece of the pie.