The drawback for me is that it can be very complicated to set all of the variables. The units that have a computer interface help with that. I guess that's why I like my EX-7. It's a multi-effect unit, but the effects are limited to seven (eight if you count volume pedal) and everything can be adjusted with the knobs on top.
I agree....that was one thing that steered me away from some of the multi-effect units. Setting the parameters with menus is much different than a simple interface like on the Boss ME-50. I really like my ME-50; it's the best of both worlds: you can use it on manual mode and just tweak the knobs as you would on regular stomp boxes, and you can also store patches easily without scrolling through menus. I'm very satisfied with the ME-50 and find it to be alot of fun.