We had consistent serious problems related to EBS for a several-month streak about a year ago, and I heard almost identical stories from other EC2 users around the same time. Instances with EBS attached would suddenly become completely unreachable via the network. Sometimes we had to terminate the instances, but usually we could revive them by detaching all (or most) of the EBS volumes, then reattaching and rebooting. Amazon seems to have fixed this problem, but I wouldn't be surprised if we suffered in the future the way reddit has.
Overall, EC2 is a very impressive offering, for which I commend Amazon. At times, I've been so frustrated that I'm ready to switch, but they fix things just quickly enough that I never quite get around to it. In the end, I'm willing to accept that what they're doing is hard, there will be mistakes, and it's worth suffering to get the flexibility and cost-effectiveness that EC2 offers.
Overall, EC2 is a very impressive offering, for which I commend Amazon. At times, I've been so frustrated that I'm ready to switch, but they fix things just quickly enough that I never quite get around to it. In the end, I'm willing to accept that what they're doing is hard, there will be mistakes, and it's worth suffering to get the flexibility and cost-effectiveness that EC2 offers.