Just adding my voice to confirm what others have pointed out already. I've been using the General HD for about a month now (the beta version), and yes - it's generally nicely recorded, and it covers a lot, but it lacks strangely at some places. There's also lots of sounds that I can't really imagine I will ever need so many of (like plenty of Curling sfx, lots of different music boxes, typewriters/adding machines... I mean it's cool, but very specific, so I'd rather have a had a little less variation in those and more variation in the bog standard fx).
Still, I'm very happy to have this as a library, there really is a lot of good stuff on it. And what it definitely has over 6000 is consistency in recording quality. There's still the trademark SI produced/designed sound to some of the fx though, but in 9 out of 10 cases it's not over-done and the sounds remain useful and easy to manipulate.
I also think that some sounds have been recorded with mics extending above 20kHz, because pitching down sounds sublime on those.
Ah, and kudos to SI for not reproducing the dreaded electricity sound fx from 6000 that I hear in every videogame, tv series and film! Maybe finally we can all move on and create our own electricity fx now? It really only takes some boring crackling and zapping noise and funky filters with LFO's/envelope followers... ;)
All in all I would say: if you want a large 96kHz library, this is currently the best you can get. I demoed Sonopedia (they have a nice system for that online if you show interest in the library), and I didn't like it as much, as it contains a lot of synthesized fx, and not a lot of variations on recorded sounds either (at least that was my impression).
Just fill up the blanks with specialist libraries from the well known boutique SFX companies (Tim Prebble, The Recordist, Chuck Russom, Rabbit Ears, Boom, Tonsturm, etc etc) and your own material of course, and forget about Series 6000! :)