I've placed an order with Bitzbox twice now, and I have had no problems with them. First order arrived one working day after I placed it (Was placed Friday night, arrived Monday morning), second arrived 2 days later. So their despatch is very good, as I was expecting them to arrive a lot later.
If there is anything to fault (and it's a small niggle than a problem), is that quite often certain bitz run out fast and takes some time to replen, which I understand is an issue with them getting parts from GW themselves and am willing to wait for as the prices are worth the wait.
I rarely shop online as I have serious trust issues after being severely done over a few times, but I have no problems with Bitzbox and will continue to use them in the future.