Yes, very excited, I think he'll be great for us. In fact, I can't wait for all the "I am sorry I doubted your b-ball skills, JG - I beg your forgiveness" threads 
+1 ACF for the first sentence of your post.
Regarding the second part, don't hold your breath for any
mea culpa posts. People here seem pretty entrenched in their positions which seem to correlate pretty highly, although obviously not 100%, to their original positions on the Perkins trade.
Last season, admittedly a frustrating one, this board was pretty evenly divided (almost to the point of bitterness) over the Perkins trade. (As an aside, I was pro-trade.) Many weren’t even giving Green a chance because of their stance on the trade.
Green is young (just turned 25) definitely has the athleticism and bball IQ (his Hoya coach called him the smartest bball player that he has ever been around!) and room to grow to become a significant piece of the Celtic future.
Last year he had many things stacked against him.
1.
He was traded for Perkins (whose value many around here grossly overrated, especially in light of his injury history and his very high likelihood to bolt anyway at seasons end).
2.
He wasn’t Kendrick Perkins.3. He came from a system that was significantly different both offensively and especially defensively.
4. He had confidence in OKC mainly because he was a peer with the stars of the team,Westbrook and Durant, in terms of age and league experience. Here. each of the big three are significantly older and more accomplished than Green.
5. He wanted to please so much that he
did think too much instead of just playing and deferred way too much to G, A and P when they were on the court and never got the ball when the black hole, BBD, got the ball.
6. The floor leader (RR) was pouting for a significant amount of time after the trade and is never very shy about how he feels. While nothing was reported on this, and it is purely speculation on my part, I believe that Green felt Rondo’s resentment about the trade of his BFF, Perkins, both on and off the court.
7. He was forced to play out of his natural 3 position because of our lack of depth at the 4/5 due to the injuries.
I very much hope we sign Green and he gets a chance to prove himself here and show us all his talent and versatility.
He never had the “deer in the headlights” issue that he had most of last year with us before. He was big-time clutch at Georgetown both during the regular season and in the NCAAs, a pretty big stage, and seemed very comfortable in OKC.
Confidence to be borne out of familiarity with the system and the other players here and acceptance is the key to his future. I hope it is here for him, at least this year.