I had been a vStoike customer for a year and half.
This is along with Selectel, the only Russian ISP which I have used over the years and I'm kinda happy with. Their pricing is very reasonable and they had been reliable in my experience. My service is stable, only with some network blips from time to time.
Speaking of the network: they have switched upstreams a lot over the last year. I don't know their motivation, but it's a bit weird. Throughput is limited and has always left a bit to be desired: it's usable, but should be better. I suspect they apply some heavy throttling (which is not present for IPv6) among other problems (like today, that I can't pull more than 5 mbps from LeaseWeb). It would be great if those got fixed, but I don't see it happening anytime soon.
Other hard thing to understand is how AES-NI is not available inside the VMs. It's 2016 and this should be supported. But for the price I'm paying is not like I can complain much about it.
The support is a bit of hit and miss for me. For normal tasks, they are accomplished fast and without problem. They even solved a routing issue which I reported with one of their upstreams within an hour, which was impressive. On the other side, I contacted them twice about the throughput problems and they could've arguably been a bit more helpful, but service is as good as I can get in Rusia for this price anyway.
TL;DR: stable service, decent support, don't expect a lot from the network. Host with them if you need a server in Russia, use a provider in the west if not.