To be fair, the pile-on of cynicism was a mile deep when the iPad was originally announced. Where are the feminine hygiene product jokes now, hmmmmmmm? ;-)
The cynicism about the iPad is still valid. There's some revisionist history amongst "i told you so"ers that paint pre-launch iPad cynicism as being about it's success.
The actual pre-launch cynicism was "this is just a big ipod". The reason for the the cynicism is because there was a geniune belief that the ipad was going to be something breathtakingly different, something akin to the original iphone (or the courier). I remember the coverage in the months leading up to it, and people were predicting off the wall things that didn't turn out. I remember one prediction that the ipad was going to be just screen that is powered (wirelessly) by your iphone, for example.
The cynicism was "this is all?". It's still valid today. There are many people who have written about how their ipads are collecting dust. There's a novelty to it that wears off, to some degree (to some people, certainly not every one, I still use mine fairly often).
But what I don't remember is "this thing isn't going to sell".