My brother got the first 4 seasons on DVD last Christmas and I finally decided to watch them. This show really is right up there with some of the funniest shows ever which is surprising with today's trend of hit and miss shows. At least with the episodes I have watched (seasons 1-4) there really isn't any dull episodes.
One problem I have is that they do get a lot of things wrong when it comes to the geek things the reference. Honestly I can't remember most of the things but the major thing I remember is the World of Warcraft references they make. The things they reference from in-game and the things they say they do in the game don't even exist. Instead of saying the actual in-game things and giving a shout out to their geeky WoW playing viewers, they make lazy made up words that just really annoy me. For a show that boasts that they get their information correct, it's a pretty big problem. It wouldn't be much of a hassle to just look up things from the game and add it to their script, and it would even make WoW playing viewers love the show a bit more.
Since I don't know every science reference they make, I really can't tell if they are getting it wrong, but from things I have read from people that do understand them, the show surprisingly does get most, if not all of it right.
If you have not yet watched the show I highly recommend you do. I'd hate for anyone to miss any show that is so highly praised as The Big Bang Theory.