I am using BlackVPN to overcome the Great Firewall of China. So far, all is working well. Connection is simple and quick, no problems to report. General browsing is reasonably fast. From most locations (including my home connection) I can use PPTP but on some wireless networks away from home this does not work and I need to use OpenVPN.
I am using the UK service in order to watch TV from home. My only gripe is that this can sometimes be slow to load, and at peak internet usage times here in China, it can be unwatchable. I'm assuming, however, that this has more to do with my internet connection here than it does with the VPN service.
On a couple of occasions (and I mean literally twice in two weeks) I have been unable to connect to the service, but this problem has lasted no more than 5 minutes, after which all was well again.
The point most strongly in BlackVPN's favour is the extremely good value it offers. If you have a code from a friend who's already subscribed to the service, it's possible to get three months' usage for €5 (1 month subscription + 2 months free). Furthermore, if someone uses your code, you get a fourth month free. This is a very generous offer, and there are no catches or small print about availing of two offers at once.