This was a real tough one to evaluate fully then and nothing's changed. I think we all assumed a center would be brought in via a second move but the trade market was next to nothing with the lockout looming. There's still a chance to bring in a vet bottom 6 center as it's a pretty damn glaring need. So long as the center position is patched up enough to make it through the season, then I have no qualms. Worst case scenario is that the issue isn't adequately addressed and, well, hopefully we get a top 5 pick out of this truncated season.
Sabres gave on value (at least on talent) to do a bit of house cleaning and get tougher to play against. It's a good trade, especially mid/long-term (assuming he stays, or is as likely to stay as Roy was) with solid youth in the pipeline at center. We all have different feelings about Roy and whether he was a 'cancer'/'underachiever'/etc, but I think we can all agree that we'd rather have Ott as an influence over our latest batch of young players than Roy.
Still, over the next couple seasons, we better hope some combination of young players (Ennis/Hodgson of course, but Grigorenko is also a possibility), non-natural centers (Leino/Ott), and bottom 6 vets (McCormick/Porter/Ellis/anyone they bring in) can do a decent job at this most important position. Longterm things look fine but things could get ugly before they get good, and Roy would obviously have taken a lot of that burden had we not moved him.
Regarding Pardy, he was a throw-in. Whether his addition proves to be useful or not shouldn't really be considered in evaluating the trade as they obviously wanted a low-level vet and if they didn't get him thrown into the deal they would have just signed another similar player. At worst he's going to help keep the organization deep with defensemen even through injuries in Buffalo and Rochester.