B&W 4x5 is incredible. Definitely get a spot meter, because it's all about placing your zones perfectly and getting amazing negatives--once you've printed off of large format negatives, you'll never be happy working with anything else.
4x5 makes you think a lot more when you're shooting, too. I keep probably 40% of my negatives from 4x5, whereas on the rare occasions I use 35mm I'll be happy with one shot off every roll or so. It's a very slow and careful process, although you definitely aren't bound to any formal principles if you don't want to be.
Big negatives also give you more options in the experimental realm of the darkroom, if you're into that sort of thing.
If you have any specific questions give me a holler, I shoot probably 80% large format.