During today's CotCT game the party fought an Otyugh and grapple was used often. I thought it worked out pretty well. The Paladin was grappled and got out and re-grappled a few times. Other PC's were able to avoid the grapples do to the bad rolling.
(I think the +1 CMB bonus is too small. I think +2 would work better.)
(Also the Otyugh sucks as a monster that has grapple since it has an 11 Str.)
During the Shingle Chase Trinia was grappled and escaped several times before finally being pinned. She laid out a few hits for dinky little damage. But I thought it worked well. None of the characters have Improved Grapple.