I played through the DLC last night and this morning. It was a lot of fun (still have a couple side missions left) and I got a couple nice guns out of it. The 2 bosses at the end are tough as shit. I joined a random group and we beat Hyperion the Invincible after about 7 tries.
We tried to fight Master Gee and got our asses handed to us. This fight is different from every other fight you've had in Borderlands. We figured out what to do but we couldn't survive long enough.