I got hold of a copy yesterday, and I'd agree that maybe it should be seen as a bit of anniversary fluff - a bit like Doctor Who's get-togethers every ten years or so (but is this
The Five Doctors or
Dimensions In Time?)
I can imagine a casual reader expecting a traditional adventure getting confused with all the post-modern weirdness. Hergé's drawing of himself being menaced by a whip-wielding Tintin was kept private, but here everyone can see Uderzo getting all his teeth knocked out by Obelix! Actually, I found the "what if they really were 50 years older" section faintly depressing with its decrepit versions of all the characters, but that's probably because I've entered my 40s relatively recently, and like Obelix, sometimes have problems with the passing of time!
Anyhow, at the very least it's nowhere near as toe-curlingly bad as
The Falling Sky, and it could be said that Asterix and the venerable Albert have earned the right to be a bit self-indulgent. I've linked to a BBC article below, which, apart from slating the post-Goscinny books, suggests that Uderzo's got some new talent in place to take over the series:
http://news.bbc.co.uk/1/hi/world/europe/8319196.stm