After hearing about all the problems people here have with the smart covers, I would never use one. I just received my Bear Motion case and has magnets that will enable/disable sleep just like the smart cover and it only cost me $35.99 and is made of leather. I got it off amazon and it only took 2 days to ship with free shipping! But I am still getting acquainted with it.
I have never had an issue with my smart cover. It does everything they say it does. I have noticed a difference in the poly one (i have the leather) where it doesn't seem as soft and flexable.
If you're not averse to a bit of DIY, there's a fairly simple solution to the "flop" problem with the SmartCover. Simply purchase a cheap "feeler gauge" at your local hardware or auto parts store. Take one of the very thin metal strips in the feeler gauge and glue it to the back of the case at the bottom where the SmartCover comes in contact when it is folded over. The metal strip will hold the SmartCover in place.
That's a good point. It's worth noting though that use of the SmartCover with the ZUM back protector or the use of any of the single piece screen+back cover eliminates the possibility of "taking it off." One of the features of the SmartCover I like is its easy detach-ability. But some folks find that to be a problem if they're prone to picking up the iPad by the cover.
I don't have that problem. But I also don't try to pick up my daughter by her hat, either.
Incase makes a back case that has a magnet that grabs the smart cover when folded back and works great. The speck smartshell does as well but still doesnt hold all the time. I liked the incase better http://www.outfityours.com/incase-mag-snap-case-for-ipad-2-white/