The company I work for is backed by a bunch of data in a MySQL database, scripts to aggregate and process more data into that database, and simple internal webapp to both manage inventory, track tasks and run lots of reporting on the aggregated data.
We made do for quite a while on a single colocated database with 32 GB of RAM and a few fast SSDs (for the time, which was about 6 years ago), and a few multi-TB archival drives, but disk space is a concern since our compressed innodb tables are well over 100GB now. I set up a Google Cloud SQL instance (the largest possible at the time I believe, 104GB RAM, and enough disks to hit peak IOPS) a few months back in preparation of migrating the data store to it, and found it wholly inadequate for our needs prior to even getting it going.
First, the second generation instances don't support being a replication slave to a non Cloud SQL instance, making migration a pain. Second, just running through the replication logs on a client and piping it to a connection to the cloud SQL instance showed that the cloud SQL instance was just barely able to keep up with the insert and update traffic from the replication log, even while handling no other queries. Catching up the the master would take over a week, even though the backup was from less than 48 hours prior.
We signed up for an actual hardware server from Rackspace at about 2/3 the cost, but with 128 GB of RAM (which I can request expanded), and nice hardware RAID 10 of fast SSD drives, and tons of logical CPUs. It's appropriately faster compared to the original database server, to the degree you would expect from from stats quoted. It fits our needs, because really I just don't want to manage the hardware anymore (this the decision not to deploy more hardware in the local datacenter we are colocated at), and that's covered.
On demand spin up/down of resources and per-minute billing is nice, and I've used it to good effect for non-database resources before, so I understand the versatility of it and how it can really enable some new types of usage and am a fan of that aspect, but I just wasn't prepared for how substandard the DB offerings are if you actually have any sort of load. At this point, the only good thing I have to say about the higher end database offerings is that they were quick to destroy so I didn't get billed anymore. :/