I enjoy using my RB. I like the ergonomics of handholding with the left hand bracket and prism finder. Yes, it's heavy, but it makes you feel like more of a man when some other joe schmoe walks past with a Canon rebel and 18-55 with his jaw dragging on the ground.
I use the 50, 90, 150sf and 180 and they are all fantastic. Once I got my focus screen calibrated they were even better. Buy it and don't look back!