In general I have to say that Ops are pretty good. Problems? I think the main one is the communication side.
Ongoing problems - we write it on a return to Ops Dept, and nothing happens. Who knows where these notes go, but I don't think Ops see it!
Big problem this year? Getting re-routes to improve the slot (great) but not actually being told that the slot improvement is due to a re-route. Finding out when low level, climbing out on a SID and being given a "direct to" somewhere we haven't heard of - not a good time. It has happened quite a few times in the last few months. Then trying to get some foreign ATCer to find out and read out the whole of our route, in a strong foreign accent, can make the initial climb go much quicker.
Once we were pretty tight on fuel, as the route was longer. We ended up negotiating to avoid a tech stop.
We do carry phones on board, and a quick phone call with the basic route is much appreciated.