I started playing when v4 was just moving into "wide beta", and honestly it was a pretty solid experience for what I was doing - mostly drafting and sealed. I had a few games lost to server issues, but they always refunded the entry fees whenever that happened and they let you keep any prizes you won, too. The stability has improved quite a bit over the past couple of years, too, to the point where now the only problem I ever really have is wireless blips causing needless disconnects (do some retries on a timeout, folks!).

There was one day where v4 was down, so I got v3 to try to keep playing. For all the people saying v4 is a step down, I want a hit of whatever it is you are on. v3 seemed worse than apprentice, which I am pretty sure I played on windows 95 when it first came out. I think the commentary on features/UI is almost completely dominated by people who are curmudgeonly and view any change as bad. I can't really speak too much to previous version stability, but right now things are good.