Route 53 is becoming a viable alternative to enterprise providers UltraDNS and Dyn. Performance is solid, but features have been lacking. This is a popular feature those providers charge $100+/mo for versus $0.75/mo on Route 53. Monitoring capabilities are limited (tcp and basic http only), but for many this is probably sufficient. DNSSEC is another feature I hope they will support in the future.

A few months back I wrote a blog post on the topic of managed DNS provider comparisons (performance, market share, price, features, network size, etc.):

http://blog.cloudharmony.com/2012/08/comparison-and-analysis...