The storage i/o speeds were also crap (quoting myself here from the notes I made at the time) compared to what I got soon after when I bought a 70€ TLC SSD as upgrade for the laptop-server. They claim it runs on SSDs but, if it does, they're the world's cheapest bulk data SSDs or they have a bottleneck in ferrying data between the SAN and the VPS host, even for sequential r/w (that it has higher iops latency, I could understand)
At work, we sometimes use AWS GPUs for password cracking (we do security audits and sometimes find hashes). The GPUs that employees have just to play some games are faster than these and cost a lot less to operate, but we can't put customer data on private systems
For occasional problems that can be parallelised, sure, rent a hundred temporary systems at a cloud farm for two days; but in general I just can't recommend it to anyone. It costs an arm and a leg compared to cheaper providers or buying hardware yourself (if you're into being the sysadmin). The "we have a fleet of systems on stand-by for you" (so you can scale on demand) is a big premium that most seem to be unaware of that they're paying implicitly