It's an ok signing imo. I would much rather have Amare for 5 years than Joe Johnson for 6 for instance. He could also do well with D'Antoni again.
Who knows what Lebron does. Personally I think he should go to the Knicks because it would be the place he could be bigger than anywhere else if he wins. Go to Chicago, you are in Michael's shoes. Go to Miami, Wade is already the man there so you will have to unseat him and that situation could blow up over time. Stay in Cleveland, the people in Ohio will love you but you will never be what you could be in a big market.
I hate the Knicks and I don't really care much for Lebron personally (love the talent but he is just another spoiled, arrogant, uber-athlete). Still, if I were Lebron and had that kind of ego where I wanted to truly be King of all sports I would go to NY. There is no other place where if he wins multiple titles he will be as big as if he goes there. Can you imagine for instance a NY/LA Finals with Lebron vs Kobe? I hate everyone involved but that doesn't mean I can't see how that would be the biggest thing ever in the NBA if it happened.