I get on well with my MIL. We respect each other and are careful not to step on each other's toes. She is kind and helpful BUT she lives down the road from us, likes to be in control and sees 'her family' as her and her children (DS, as her grandchild, is probably also included).
We have no issues and, I think we both try to include each other, but I do feel suffocated sometimes. At times, my life is made much easier by her taking control and sorting things like Sunday dinner or Christmas, but equally I feel that I am not able to start or incorporate my own family traditions and that we (DH, DS and I) are not seen as a family of our own. I am merely an 'inconvenient' addition.
I also feel that there are times where she tries to compete with me on the 'mothering' stakes, which is ridiculous as she has 3 grown children and I have one 21 month old and an impending newborn. She does like to show-off in front of other people and say things like 'oh, what a horrible mummy, come to granny' or 'DGS loves me best'
For the most part I ignore it because in every other way she does do her best AND the relationship with her own children (especially SIL who doesn't have children's herself yet) can be similar.
Over all I think what I am trying to say is that we get on, we both try hard, I try not to include her and she tries not to step on my toes and it works but only for as long as we both respect each other's boundaries and aren't too precious about our own. If the delicate balance we currently have where to change (and sometimes I feel she does push it) it could easily tip over into a less congenial situation.