There is no denying the historical significance of this event. It was the charitable event Live 8, a global concert for peace, that gave them the reason to put their differences aside. They'd occasionally play on each other's tours over the years. But the reality of this show is they were not a practice band. These were songs they'd played a million times, but not together for a very long time. Instrumentally, they were fine. Fine isn't what you would want from such a talented group. Vocally, they sound old. Waters sounds excited to be there, but his voice just doesn't have what it takes to keep up with the demands, at least not in this show. Gilmour sounds OK, his voice is stronger, but he doesn't sound like he really wants to be there. One is willing but lacks strength, the other strong but lacks will, there's a Floyd song in there somewhere.
So in essence, this is a piece of history, but not one that you will want to revisit that often. Both Gilmour and Waters have live albums with better performances, as does Pink Floyd, so if you are looking for a great performance, check those of first.