I've had several attacks hit my services on OVH. Not once did they null route, and as far as I could tell the majority of attack traffic was filtered with only a minor service interruption before mitigation kicked in. Granted these were shitty $10 booter services hitting me and not a "real" DDoS.

Be careful using services like game servers or VOIP or anything else using UDP though, since UDP is subject to much more stringent filtering at OVH and may get affected during mitigation.