This reservoir is pretty out of the way if coming from the denver metro area as it's about a 3 hour drive. We wanted to try it for the long holiday weekend since we have more time. Overall the reservoir is huge but it's not really been built up enough to handle recreation activities for people. Even fishing seems hard and many people also brought boats.
We camped near Lake Hasty which is next to the reservoir but is very tiny with better access. Even with better access it's hard to get in to the water. We thought the campground would have access to the lake but instead you have to drive to the other side of where the campground is and get in, otherwise there's not any other way in due to the reeds surrounding the lake.
Once in, it's beautiful and calming especially if going in the morning before the rush. There were a million blue dragon flies when we were there and maybe fish but I never saw any cresting the surface. I did see a few turtles and a couple of ducks.
As for the campground, don't stay in 1-29, as there is virtually no shade on that side. The other side was covered in large shady trees.