This comment further down, supposedly from an Amazon employee, paints a grim picture for EBS: http://www.reddit.com/r/blog/comments/g66f0/why_reddit_was_d...
The team develops a reputation internally for being glorified firefighting, and have trouble recruiting. More senior engineers eventually flee (having, well, choice in the matter) leaving a team heavy with junior talent with no seasoned gurus leading the way.
The company is also growing at ludicrous speed, and hiring is difficult. When the product is in such a painful state, attrition from the team is high, and with slow hiring you are barely countering attrition (exacerbating the junior talent problem), and not even close to growing the team to be in a position to take care of the problem for good.
I suspect this is an industry-wide problem though, and is hardly unique to this place.
My gripe with EBS is that hiccups in EBS cause my Linux instances to "lock up", consume 100% CPU and become unresponsive. AMZN is providing their own Linux distribution and drivers for the EBS devices so they can also attack this problem by patching the Linux kernel.
I'd compile my own web server stack, but it's as good a foundation to build on as any Linux distribution.
I'm surprised Reddit ever though AWS would be a good platform to host on. You don't bitch about it, you create the best system you can and if something doesn't work, then you need to do more work. If you don't want to put in the work, then AWS is wrong for you. You don't see Heroku bitching about AWS, rather they made the thing work for them with great engineers.