My in-laws are/were fantastic - I couldn't have wished for better. MIL is still alive and is lovely. In fact, even though she is in poor health and 84 she does remarkably well. She was widowed in 2001 and in 2002 we took her for her first trip abroad - as it was something she always wanted to do, but FIL wasn't interested in foreign travel at all.
That's not to say FIL was a bad person - he was just born in a different time and was 90 when he died. He was wonderful too.
They treated me like a daughter from the very first day - even though there is a 15 year age gap between hubby and me, they never made anything of it - unlike some of my own family.
When I went to University in my mid-20s, they collected the children from school and looked after them til I came home - in fact, if I tried to collect them in my vacation time, MIL would get upset that she was missing time with the kids (when I was just worried about putting on them too much). I knew if I needed anything, at any time my in-laws would be there with no questions asked - and they know they can rely on us for the same.
Sorry it's a bit long - but when people are wonderful you just want to share them don't you