Brilliant and very very sad.
Here’s my analysis of the situation. Just incase I’m going to put it in a spoiler box. You need to see it fresh.
Angel said that he was making terms of the deal and so he secured the new life for Connor. The key is that it isn’t Connor happy with Angel as his father, or restored as a champion. Angel finally realized that he has been selflish about the Connor issue. Yes Angel loved Connor but more than that Angel wanted to be his father. He wanted to have a son and to raise him and to guide him. Yet that simply wasn’t possible, so finally he let Connor go. He gave Connor a real, and good, life. In the process Connor vanished, probably it is just a memory thing but who knows. Angel was willing to make a long lasting deal with the senior partners and give up any chance of having Connor to save him.
As for Gunn and the panther I’m not sure. I have the notion that it was a representation of the beings that the little girl used to channel for Wolfram and Hart offering to make Gunn their new conduit. However I think it has to be something more than that, some offer of making the world better in a direct way, to get him to accept.
A simply amazing hour of TV.