It's OpenVZ, not full virtualization. That means you have no control over the kernel (e.g. can' t upgrade it, can't fully reboot), and it's said - but I can't vouch for it - that it's more susceptible to "bad neighbors".

They have full virtualization (the VPS Cloud plans), but it's much more expensive.

Here's a thread on Lowendtalk about VPS Classic plans: http://www.lowendtalk.com/discussion/37835/ovh-classic-1-vps...