Two weeks might be a tad optimistic since I've been running a bit slowly (real life intervenes). Basically, the game works but there are a few areas (e.g., mind flayer jail) or concepts (e.g., NPCs leaving the party, doing work and then rejoining the party) that don't work well.
Up to this point all of the effort has been focused on stopping the thing from crashing and making sure that it mimics BG2 fairly closely. It pretty much doesn't crash anymore and the mimicry levle is high.
In a few days we'll move on to more serious game balance testing and discussion. The beta is only "closed" in the sense that you have to email me about it if you'd like to participate. I encourage everyone at Ironworks to take a look, especially when it comes time to debate the difficulty of the converted battles.