Another thing to consider is latency, which means the time it takes packets to reach the next hop. The latency between your phone and the cell network is really high, on the order of 200-800ms. In DSL its around 10-100ms. A high latency means VOIP applications wont work correctly (skype, magicjack) and video games will suffer from incredible lag or will just be unplayable.
Bandwidth is another concern. Sure, when you download a webpage it runs pretty quickly, but once your cell provider realizes you are doing sustained transfers of files they will throttle you pretty quickly. Ive found the major carriers will throttle you down to near dial-up speed and there’s nothing you can do about it.
Lastly, dropped packets and reception are problems. One day you’ll have great reception and the next you wont.
If youre willing to live with these limitations then go for it. You can do the BB thing for a week and see how well it works for you. I would first call the cell company and tell them that you dont want to pay any data overage fees. Tell them to just disconnect you if you hit the cap. They will happily send you a $5,000 bill if you go over.