Well said @
Scarecrow. I am a long time mythtv user and more latterly an xbmc afficianado. I came to xbmc because I like to experiment and because I heard it would do a better job of scraping metadata (I am not talking PVR right now). When I came to XBMC it didn't have a standard PVR interface, but did have a couple of unsatisfactory methods of interfacine with mythtv.
Move on to now and XBMC's PVR is pretty good for us. I have to say that my entire family (kids 19,18,15, been living with mythtv for 6 years) don't channel surf, because they have grown to "record what you want to watch, watch when you want to watch". I know many don't agree, but it suits us fine. They can do live tv, and channel surf, but generally don't. Similarly the EPG is not that important because we tend ot set up recordings on a web browser. So channel change tme is not so important to us. Reliable series recording and duplicate recognition, and flexibility ae important, and our setup gives us all that.
Anyway, the PVR interface in XBMC has to cope with a huge variety of backends, and considering that requirement it is bloody remarkable.
As far as fanart/images etc is concerned, is that a backend function or a frontend function? I say backend (logically you don't need 6 frontends searching for artwork, when the backend can do it once). But some backends may not have that capability.