I'm happy. I couldn't put too much slope in but we do have a couple of features that affect the ball. Mine is about 450 sf with three cups, that is plenty and I can roll some 22' putts to check my tempo. It rolls true, though I think I need to invest in a landscape roller to roll it every few months or so. SWG will come out for a very nominal fee every couple of years to check everything and roll it if warranted.
We rarely putt from edge to edge unless I have a couple of buddies over, usually we play chipping games if anything. Way more fun, since we always two putt from anywhere on the green (for the most part)
If I had limitless funds and space, it would be bigger with more features for chipping and ptiching. Though we can hold shots from the upper deck, which is about 35 yads away. As far as putting, I spend most of my time honing my stroke from 8' and in on the area of the green that I had the guys make dead level (I checked it myself prior to the turf installation). As far as game improvement, that has been the biggest factor.