I've been flying them for a number of routes and while I miss the upgrades to F, for a quick jaunt up or down the east coast I can pass on that. I actually have a LAS booking coming up, and I'll see how well I like the A319s for the longer routes.
If they'd had double points since the beginning, I'd be really close to an award ticket after my LAS flight. As it is, I'll probably need one expensive flight or two cheap flights in addition. Like WN, that'll be useful if I have some last-minute issue come up and the fares are $299 each way plus taxes.