You need to be prepared for halting failures and variable performance. Moving from higher end, dedicated hardware to lower end, shared hardware means an increase the failure rate and in the variance of your latencies. In exchange you get elastic scaling, you convert capital costs to operational costs (no more building datacenters), and you hand the "undifferentiated heavy lifting" to AWS. The posts aren't, IMO, understating problems but demonstrating the tradeoffs that come with AWS' core value proposition.