Going to class may or may not improve your understanding of the law. But what class will almost always do is give you a window into what the prof wants.
If you skip out on class, how will you ever know that the professor LOVES policy arguments, and expect to see that on the exam? How will you know that the prof rejects one of the main points/theories in the casebook, and will teach his own "pet" approach?
Just suck it up and go to class. Do whatever, surf the net, play solitare, etc. But keep an ear out for the stuff like I mentioned above.
And who knows, if you just relax and go with the flow during class, you may learn something. (I would guess that if you're automatically assuming that class will suck, and that you're getting stressed out as soon as it starts, your frustration level will rise almost immediately, guaranteeing you won't learn anything)