I have a J-Station and I think it sounds great as far as modeled amp sounds go.
I prefer using a real amp of course. Real tubes pushing real air can't be beat. That being said, the J-Station actually sounds better than the POD, and the V-Amp. (The V-Amp is junk).
I don't know about recent pods, but the old ones were only 16Bit also. The J-Station is 24bit, with spdif, so you get a nice clean recording. Now, many people get fooled by the pod because they have cooler effects patches and sound better on first listen, but for getting an amp-only sound the J-Sta rules. You don't record with too many effects really anyway. FX are usually added in the mix, so you really just want good amp tone. Me and a friend ordered a Pod, a J-Sta, and a V-Amp all at the same time to compare them, planning on returning the 2 losers. We "A-B-C" compaired them for a good hour or 2. The J-Sta won hands down.
The thing that I have noticed is these modeling amps sound better than they feel. While playing and listening through speakers they feel soft and a little off somehow. Probably because you aren't feeling the volume in your chest. But when you listen back to the recordings they sound pretty real. I have had complements from other producers on guitar tracks I recorded as scratch. I tool the J-Sta to my drummers house to record his drum track, but I plugged in my guitar through the J-Sta, and the Bass plugged in straight, and we all recorded with headphones. I didn't want bleed so the J was the way. Anywho.... When dumping the tracks from the ADAT to a friends Mac, he thought I had miced up a nice guitar cab for the recording.
Bass is pretty good too, but I haven't used that in a ling time, but I remember a couple of patched I really liked. Sansamp may be more the ticket (I haven't tried one, but I have heard they are the shiznit). The thing is that Line 6 had the marketing and beat out the J-Station until it was discontinued, but the fact is that for straight amp models the J is way better, and a higher resolution (24bit).
The software is easy to use though you need midi link up to that. You can get mucho patch files from the J-Station web site.
Still, a good amp and mic will sound better, but if you want the convenience this thing offers you will be pleased I'm sure.
Good luck.
Chadfish