PODxt has a huge range of effects and amp modellers etc. I have one and the sound is "good", very versatile but difficult to get the exact sound you are looking for. Also, no matter what you read, they are not up to professional recording quality (compared to real studio gear). But for the money they offer good value.
Digitech also offer good hardware, the best one there is the GNX-4, not cheap but it has everything. I find the sound on the GNX series a little more realistic (as far as digital realism goes) and it has some realy cool features. I have a GNX-1 and I still find myself gravitating back to it over my PODxt for direct pc recording.
All in all, I have always got the best sound from regular stomp boxes or a good amp. Line6 stomp boxes and Boss pedals are definitely up there and the ones that you see most often on front of pros in studios and live.
If you want to record into your pc, then you are probably better off going with the Digitech GNX series or the PODxt (unless you plan on forking out for a Pro soundcard or a usb mixer/controller).
From what I have heard, Shadow pickups are very good but I have never heard them or used them.