pssst, don't tell ze Zermans but the german release is actually one huge closed beta (get a key buy bying it). Not that D2 hasn't been tested properly before that release... Anyway it just means Larian can rid the International release of bugs, and tweak some features the german owners of the game pointed out improvement.
All in all, everything you said is imo wrong, reviewers give out bad scores because a game has been released later in one part of the world than another. Games don't get worse by time either, on the contrary like I said 'patches'. Mediocre games get mediocre scores as good games get good ones, looking at the german reviews, it's a good game and will only be better once released in the US.