It certainly hasn't been a flop, over a million units sold in less than a month. So I think we can assume it's not going to fail. Moreover, these are just US sales, since the international release has been delayed because of the demand. Given that the US is still struggling out of recession and money is tight, I'd imagine Apple are quite pleased with these figures.
Apple's design seems to have been as thorough as ever, very few problems have been reported. Some people have had WiFi reception issues, but these seem as much due to the wireless network's settings as the iPad itself. A very few people have reported over heating and there has been misunderstanding concerning slow charging via USB when connected to a laptop rather than the docking station. None of these issues seem significant.
On the plus side the battery life seems better then stated by Apple, and consider how often that is the case (never). Several games (e.g., Scrabble) are excellent on the iPad and as more and more apps roll out we can still only imagine how useful it will be in the future. Most users find watching movies, TV shows and reading magazines on the iPad a pleasure and the iBook reader is easy to use and not a strain on the eyes (I'd imagine Kindle have had a few interesting meetings this month).
So I'd score the result after a month:
Apple: 1 - Nay-Sayers: 0
[The iPad still isn't available in NZ, but I have touched one]