Sabres fans are a bit too upset. Your GM didn't crap the bed IMO, he was playing from weakness. (For the record, I'm a Panthers fan.)
The deal was actually close to fair, with Florida coming ahead BUT the reasons have been listed. 1) Reino wasn't going to stay, and everyone knew that, so value keeps going down, best to do a deal now. 2) Levi only doesn't look that good of a return because Panthers Goalie depth (and that's not counting anchor Bob) made him "look" more expendable. He's proven plenty of people wrong already. 3) Buffalo probably got the best deal on the table because of uncertainty of Reino contract. 4) Zito was willing to roll the contract dice because his team looks good on paper and almost all players want to win at some point, Reino maybe thinks this is perhaps the chance of his career.
In summary, Sabres fans IMO are mostly upset because the deal wasn't painful to Zito. That alone doesn't make it awful. Buffalo's hand was severely limited, they did the best they could. Zito was looking at other pieces too, so unlike Flyers, he was willing to walk away. You always have to be willing to walk away if you want a good deal. If Buffalo waits, then fans yell "he got next to nothing for Reino when he could have got a first before the season!!"