My biggest peeve with the Beo5 is reaching for the top left corner of the touchscreen with my thumb, and my palm squeezes the Standby button. The Standby button is huge and too easy to accidently press. Also happens sometimes when trying to select Blue.
Aside from that, I have a BeoSystem 3 with Blu-ray and Mac Mini, plasma, and projector, as well as a couple LC1's, and Beo4 was just too limited, especially with regards to controlling the Blu-ray player. At least you have separate buttons for menu navigation and playback control (FF >>, REW <<, chapter skip \/ /\). The inner ring arrows are menu navigation, and the outer ring hard-keys are for playback control.