my biggest gripe is when the gameplay difficulty is a consequence of the way the *control regime* is designed, not because I don't understand what I want the character to do. Obvious examples are games designed for controllers which map poorly onto mouse+keyboard. It takes careful consideration (and a lot of time) to design a good, responsive and powerful control interface, and sadly its a skill most companies seem to lack.

Edit: obviously I'm referring to more action-oriented aspects of cRPGs, not encounter design etc…