I got a Trek 520 almost a year ago. It's a tank. I love that bike!!! Confidence-inspiring on commutes (100% the case for me).
I don't know about the gearing problem everyone's referring to. I have stock everything, and I have no problems on hills, etc. I have a triple, so maybe that's why. It's a heavy bike but that's expected given that it's a tank. For my commute I'll gladly trade weight for the additional safety the bike affords by allowing me to ride anywhere -- good for evasive maneuvers.