Year 1 is supposedly pretty different from subsequent years - you should at least stick it out until you fall in with some research group or other and see how you like it. As a bonus, you can get your Master's!
It's mostly the course work and preliminary tests (studying for them) that I'm not liking and dreading, which are supposed to take another ~2 years. At that point, the sunk cost fallacy would probably keep me in for the whole thing.
