I play on bleeding hollow, one of the highest population servers, and I can say I have pretty much the same experience. You are constantly disconnected in critical situations, periodically and systematically lagged to death, and then there's times when it's bad. A couple of weeks ago, my guild was trying to go to MC but you couldn't stay logged on past 5 seconds anywhere in all of Kalimdor for about 4 hours. Summons FTW! Blizzard servers FTL!