First off, I'd give Walter a chance. He didn't look too shabby for a guy with 7 practices in the system. I say that as someone who identified Cassel as potentially the real deal 4 years ago...and never waivered...
As for Feeley, he's the #3 in Philly for a reason. Kolb is injured but expected back before the season. And even then they have an exemption for Vick UNTIL he is actively reinstated. So he won't count against their roster for at least 3-6 weeks...
Since this is a guy who pissed dirty during Federal pre sentencing I have no reason to believe he will not screw up or otherwise disappoint short term. That said it is the potential for friction between NcNabb, the fans, and Vick/the FO as the season unfolds that could blow this thing apart. And what he might bring to the table based on what he once was, an athlete trying to play football QB, vs. what this could do to that franchise is not a solid risk reward. Even Lurie admits that. He's there to prove some other bs point about redemption. If he doesn't, the Eagles, Dungy, HSUS and Goodell will be spending some time wiping the egg off each others faces.