Dramatic decrease in SQL Azure performance after scaling to new edition
I conducted a series of performance tests against the new service tiers (as mentioned by another poster above).  

I tested I/O rates back in July and have now also tested the memory (i.e. max buffer pool size) in each tier:
http://cbailiss.wordpress.com/2014/11/11/azure-sql-database-memory-limits-by-service-tier/

(I was going to add this as a comment on dark_perfect's comment above, but on this site I don't have enough reputation to add comments yet).