It was definitely worth it! It just put everyones mind at ease as to where to stand and how things would run (ie. what to do when we are signing the register etc). I think it was most helpful for the BMs, as one BM couldnt attend and she was nervous about where to go and and where to stand, but the others were ok because they had been at the rehearsal. Also for my dad, in the giving away part, because the celebrant told him when and where and what to say, dad wanted it to be perfect so he wanted to practice
It also gave me piece of mind that things would run relatively smoothly.
Also, Ive been a BM at a wedding without a rehearsal and we were nervous about where to go down the aisle, where to stand etc. It turned out find in the end (the celebrant just shuffled us in closer once everyone had walked up the aisle) but I really think if you have the opportunity for a rehearsal you definitely should