Seen this thread a few times but have never posted in it, here goes my lot. Mostly good experiences, I must say:
Rupert Grint- Really really lovely, which I was thrilled about! Love Harry Potter and he didn't disappoint.
Ben Whishaw- Nice enough but a little aloof, think he's perhaps just a little shy.
Colin Morgan- Really pleasant and easy to talk to.
Brendan Coyle- A very funny and nice man.
Rob Brydon- A bit of a mixed one. Saw him once and was sworn at for saying 'hello', then another time he was really friendly and cheerful.
Dan Smith (from Bastille)- Incredibly humble and very, very nice. Chuffed as I love Bastille.
Mel Giedroyc- Just as she comes across on TV. Really genuine and nice.
Nigel Harman- Lovely and happy to chat.
Jenny Eclair- Awesome! Really nice lady.
Louie Spence- Nice, a lot calmer than his persona but that's to be expected surely.
Kristin Scott Thomas- Not pleasant at all. A wonderful actress but she's very aware of that.
Louis Walsh- Nice enough, posed for a picture and a chat.
David Essex- Really sociable and nice.
Lee Mead, Ann Mitchell, Marc Elliot and Phaldut Sharma were all lovely too. (I'm running out of adjectives here)
I think that's everybody.