Like most folks, I prefer using Mr. Tanno....but there are occasions where I'll use Amazon Japan or HMV. HMV is definitely the best because you can periodically check in on the status of your order. It's very straight forward and you can clearly see what is still on order versus what's sitting at the ready. If you get tired of waiting for those last few discs, you just put the zap on them and HMV'll soon be shipping the remainder.
Amazon Japan is just a mess. You order 12 things from them and then wait and wait and wait.
No updates, no way to tell what they actually have in hand or how far along they are in the acquisition process. They could easily have rounded up 10 of the 12 items on your list two days after you submitted the order but you'll never know it. Six weeks later you don't know if they're but one disc away from shipping --- or eleven? At some point you just say 'screw it' and go cancel everything.
CANCEL!!!
Ahhhh, that felt good!
Damn! What have I done?