I have seen Edge put on a few great matches since his return. I would argue that the Edge/Jericho match at 'Mania was the most entertaining one that night. Also, during the commercial free Raw on 5/17, he and Christian put on an absolute clinic for a good 15 minutes or so--if you haven't seen the match, go find it. His match with Wade was also quite good.
I felt at the time that his heel turn was completely random and out of the blue, which made very little sense. While some of you seem to think that the crowd "didn't buy it", his face run was way too short. If creative didn't think it was working, they should have given him the belt and had him continue the feud with Jericho, and go on to battle other heels on SD afterward. Swagger was never ready for the main event, and look how that turned out. Now that Dolph is Vicki's arm candy, what better way to put him over than involving Edge (obviously after some time had passed and the Kofi feud ends)? There were lots of possibilities that could have emerged, but no one felt like thinking about them. Regardless, I certainly think he was over enough for it to last longer than three months. If ever there is a good opportunity to turn him face again, people are going to buy it even less after the way the last time turned out.
When he appeared on Raw and it looked like the Orton feud was actually going to go somewhere, it piqued my interest. His line about "the real fun begins" made it seem like this was going to be something epic, but I still didn't get my hopes up. Sure enough it fizzled almost immediately. His participation in the SummerSlam team and Nexus storyline has been intriguing, but predictable. Beyond that, I see no real clear-cut direction for him. If he was still face, I think a feud with Miz would be an excellent way to further the latter's career and get him even more over. He could be re-establishing his career in so many ways and furthering that of others, but all that's happening is people creating threads like this.
If things are going to work out for Edge in the immediate future, he'd benefit from moving to Smackdown to put any kind of feud on the map in what's been a really stale show lately, even if it has been done before. The only way I see Christian getting a world title is if he wins it from Edge, so that could be an interesting development, but I'm not holding my breath. Still, the two are capable of working excellent matches with each other and it would be a new feud that people have been dying to see. As someone suggested, their reunion and pursuit of the tag titles would be a great way to refresh both of their careers right now. Hell, the breakup could even be part of the world title scenario. I definitely think the booking has been crap for Edge lately and that really needs to change. He is one of the most talented and entertaining people in the company, even if he can't do everything he used to, and he needs to be utilized.