Radigast:
They nailed him. As I recall, he was a slightly eccentric, nature loving, forgetful wizard. As for the comic relief, it was all in character.
Smeagol/Gollum:
A bit of creative liberty taken here, but it was the same for lotr. I don't think it was a poor choice. Kept some continuity.
3D:
Everything that was not animated was great. I could see texture in the characters faces and such. Some of the animated stuff was thrown in your face, but it was few enough and far between that I honestly didn't even notice it. I had more issue getting used to the 48 fps, made it look almost like a documentary filming. I mostly got used to it by half way through the movie, but the jury is still out on that point.
White orc: A bit more creative liberty that IMHO did not detract from the story. Could have been left out, but it works.
Thorin: They leave his character open for growth. If they play it right in the next movies, I think it'll work. The characters shouldn't be static, and I think they are setting him up reasonably well.
Music: I'll agree with you here

Goblin King: I agree here, he was a little over the top. The way I justify it in my head is the whole "Target Audience" bit. Overall I loved the goblins, but yeah. He could have been much better.
Other thoughts: Trolls were great! That whole scene was pretty sweet. Bilbo should have been allowed to delay longer though.
Dwarf Song: Needed to be longer!
Impossible survivals: You know what I mean. Stone Giants, falling through into goblin cave, ect. So over the top, but I guess it fit pretty well still. Realism wasn't the goal for sure.
Elven King (can't remember his name, only in the beginning of the movie. He didn't help out when Smaug came): This is how I picture an elf. Legolas was not. Elrond wasn't either. Galadriel was very good. This guy was perfect. Elf to the T.
Thats it for now. Overall I really liked it, I think it'll be even better second time around now that I'm a little more used to 48 fps and have more accurate expectations.