The only complaint I have about it are that the relay they have between France and the US is nearly always congested during US prime time. Because of this, download speeds from my server are really slow around 8PM est. Otherwise it's great.
tl;dr Development box and not in EU? Do it! Production box and not in EU? Maybe go with Hetzner or someone domestic.
I've been having trouble with my existing UK dedicated server provider of late and am looking to move. I could get a lot more bang for my buck with OVH/kimsufi, but wouldn't want to move if they were more unreliable than what I have now.
Also; they are HUGE and growing fast. When I started with them in 2005, they would ONLY speak french, you could not ask for support in another language, you could not pay in another way than the french bank and so forth. And machines + network would be down often. They improved a lot, so my guess is they will improve more over time, but they are a monster in hosting land.
Thanks for replying.