No, I don't think he was "great." You wrote that the Bills NEVER (all caps yours) had a TE, and also wrote that it's an area where we've "always" been bad. McKeller won't make anybody forget Tony Gonzalez, but TEs that can both catch and block, as opposed to just catch, are frequently under-rated. My point was simply that McKeller could not fairly be characterized as "bad," even if he didn't have gaudy reception stats. McKeller's versatility helped make the K-gun work, as explained with some historical context here:
http://www.buddynixon.com/analysis/the-kgun-offense-beyond-no-huddle
But this is an Internet message board, so if you want to claim that every Bills' TE who failed to make the Pro Bowl was "bad" - - post away.