It is a fan flick to be sure - but has he changed the fundamental elements of the story? No. Has he changed the "lore" of the SW universe? No. Has he fixed continuity errors? Yes. Has he respectfully corrected clunky FX shots? Yes. Has he fixed spelling errors of crew names from BOTH versions? Yes. Sure, he's added a few new elements but if anything, he's generally paring it back to what the core of what the original was all about.
The digital work in Jabba scene (actually most of the new SE Tatooine elements) never fails to take me out of the film. Adywan has stripped many of them way back to return the focus to the story. He's added a bit of epic-ness to scenes that could have used them, and generally his choices have been pretty tasteful. Things that admittedly bugged me for years (apart from the Greedo thing) he's given treatment to, e.g. "I know a few maneuvers, we'll lose them" followed by flying in a straight line. I'm sure the only reason that the Falcon originally flew in a straight line was budgetary.
As to whether we should wait for Lucas' death before we start playing around with this, you could say that by consistently flooding the market with merchandise for over 30 years, he himself has made it part of popular culture. It has really taken on a life of it's own. Do you think he really proof-reads every SW novel or OK's every piece of crap that goes out there? Of course not. Also, by Lucas making quite dramatic changes to his own work years after the original release, has he inadvertently given license for others to do the same?
I'm a fan of SW (I'm probably coming off more obsessive than I actually am) but the older I get, the more I see SW moving away from the elements of what made the original so universally embraced in the first place (i.e. the monomyth). This, coupled with what seems like Lucas' agenda to make the SE the "true" versions of the OT (few would argue that the changes made to them actually have made a better film story-wise) makes me wonder that if there are people out there who seem to care more about the SW mythology than Lucas does, should they have the right to make their "dream" version? Adywan hasn't put his name on it, and he's not making money from it (I don't think) so where is the harm really, if it's done while respecting the spirit of the original?
Sure the guy should probably get a new hobby, but I think this "ultimate" fan-film raises interesting questions about the ownership of Star Wars as a cultural icon 30+ years on, especially since the originals borrowed so heavily from universal mythology in the first place*. I think SW is a unique phenomenon in this regard.
*I personally feel that Campbell not getting some kind of film credit or even a "thanks" in the original is criminal - he wrote the SW manual - but that's probably a topic for another thread.