Assembly on the road bike I just bought was about as hard as the basic once-over that I give my bike about once a month anyway. IMO if you are the sort that has to take your bike to the shop to do basic stuff like adjust the brakes, align the derailleur, etc then you'll need them to assemble a BD bike as well.

I understand sometimes the wheels are not true as they come. That takes a tiny bit more skill to fix but it's still not much. My rear was dead true, my front is maybe most of a millimeter out, not enough to really make any difference when riding but I'll probably fix it just because it'll bug me.