Most of AWS's major outages have been related to EBS. Although outages can happen to any hosting provider, and I am sure they have fixed the previous issues. So

Most of AWS's major outages have been related to EBS. Although outages can happen to any hosting provider, and I am sure they have fixed the previous issues. So EBS should get more stable over time and it is already quite stable. The performance of EBS is pretty bad, and getting decent performance is expensive. Having said that, if your application runs in memory and disk usage is infrequent then it is probably fine to use EBS. EBS is also much more expensive than the instance storage, but it is also durable unlike instance storage. On the whole, "never ever EBS" is too strong language making it incorrect. As usual, it depends.