Yes, I've had a few servers with them for some time.
The bandwith is decent and pings are low (which you can expect from a hoster in Francfort) and the overall quality is also very decent.
I've only once needed their support (to set the rDNS entries for a few IP's), but it was quick and friendly.
In overall, I can recommend them, altough you'll only need their services if you host ping-sensitive applications. For the usual webhosting and high-traffic applications, I'd prefer Hetzner.