I used OVH for about a year and had no problems (had no need for the server any more).
The only issue I did have (and might be worth considering) was probably to be expected: they seem to be very on top of network issues and won't hesitate to terminate your server if something is suspicious. I was running a game server (Call of Duty 1) that had a bug that allowed someone to maliciously redirect packets to someone else (not a spectacular amount, but enough that when they did it with ~10 servers it would cause problems for the victim) and because we were part of an attack the server was shut down and they wouldn't return it to me without agreement that we'd wipe the "infected" server -- even though it wasn't infected, it was a software bug that we could resolve if we had server access.
Definitely worth using for unimportant things, but definitely not worth risking it on production.
We had a UDP flood from an OVH server, and they said they contacted the customer to fix this issue. I checked the IP and it was still running a splash page.
A couple days later we were attacked again by the same IP. After reporting this to OVH again they finally took the server down.
The only issue I did have (and might be worth considering) was probably to be expected: they seem to be very on top of network issues and won't hesitate to terminate your server if something is suspicious. I was running a game server (Call of Duty 1) that had a bug that allowed someone to maliciously redirect packets to someone else (not a spectacular amount, but enough that when they did it with ~10 servers it would cause problems for the victim) and because we were part of an attack the server was shut down and they wouldn't return it to me without agreement that we'd wipe the "infected" server -- even though it wasn't infected, it was a software bug that we could resolve if we had server access.
Definitely worth using for unimportant things, but definitely not worth risking it on production.