Well, we have had 2 (two) Kreepy Krauly automatic vacuums now, and I have mixed feelings about them.
PROS:
When they are working correctly, they work AMAZINGLY WELL. It keeps our pool completely free of debris. The only thing it has trouble with is when sand gets in the pool. But sand is a pain for manual vacuuming, too.
CONS:
1) I think it's ridiculously expensive and I think the makers are basically milking their buyers because NOTHING on this contraption warrants the price tag. It's pretty cheaply made, which brings me to my next point...
2) They wear out pretty fast -- EVEN IF you take care of them meticulously! The first time I had to replace mine, I just assumed it was a hard lesson learned... Next time, don't leave it lying in the sun, keep water chemicals perfectly balanced when it's in the pool, store hose properly... yadda, yadda, yadda... But with the one I have now, I HAVE done all of those things, it's barely 2 years old and the rubber "floater wings" just broke off for no apparent reason! And every tiny replacement part is ridiculously overpriced as well, so there's no easy maintenance.
3) It gets STUCK. A lot. On the edge of my eyeball jets, on the stairs, in the corner... we're forever going out to "rescue" it and get it going. The hose gets tangled frequently, too. But it's still less time consuming than having to manually vacuum each week, so...
I guess it all depends on what you are willing to put up with.
Right now mine is working and I have 3 very active children, so I'm content to shell out some more cash to replace the wings.