Looks to be very specifically geared towards a certain type of database load. The ratio of CPU, RAM and storage is fixed, and (in my opinion) the offering includes tons of CPU/RAM with relatively paltry storage sizes.
Additionally, no built-in HA / replication options.
That said, this nicely illustrates how nearly any competent setup will run circles around RDS in terms of queries per second.
And yet I still choose RDS…