On my DH's side I get along great with BIL #1 and SIL, we hang out and go to dinner on a regular basis. I also get along very well with BIL #2. DH is very close with his brothers and we all meet up regularly. I get along well with FIL and MIL on that side, I consider them like my own parents as they are just good people.
DH's Bio-Mom (MIL #2) is another story. The woman hates my guts and has tried to break up DH and I several times. DH does not get along with her either and cut off most contact with her about a year ago. I have the BEST crazy MIL stories from that woman.

I try not to take it personally, her craziness is not a reflection on me. Thankfully she lives in another country so I rarely see her.
On my side.... well, I am sure people around here are well aware of my Brother and my SIL. I love the guy because he's my brother... I am just not so sure i like him. My SIL is perfectly nice, just a bit odd. As is the case with my brother I am not entirely sure what the heck is wrong... but it sure as heck isn't right. Exactly like my brother. They are a perfect match. We get along at the moment but we shall see what becomes of that over time.
DH gets along well with my parents and does not seem to have any complaints about my side. Sometimes my Mom's obsessive planning annoys him but this is a minor issue and it bothers me too! No real huge issues.
Our two sides of the family occassionally get together for holidays since we all live within a few hours of each other and that way there is no worry about splitting holidays. Everyone gets along well enough.