Writing from Precision 5560 (not bought. but given by employer).
Pros - good screen. Decent battery life. Compact.
Cons - cooling system is way too weak to deal with CPU (for that money they could have added vapour chamber). Melts in closed / docked state as you have 100% blocked exhaust, so can't close it, put it under monitor and work. Shallow keyboard, but that's expected, though better than on previous precision I had (5520). Only 4GB GPU, which h is a joke for prof. 3D application (I am CAD and CAE eng.). Design over function, which as a professional I don't care about.