That's true. A lot of people don't like them.
At times the carbonation is NOT consistent (BIGGEST COMPLAINT!).
HOWEVER, I have 19 of them and use them A LOT!
Now, I know that I can recommend them, but that's like saying "try broccoli...it's good", or even that squid ice cream..., but it all comes down to works best for you.
I actually have about 12 of them FULL right now. I just kegged 2-Hefe Weizens and 2-Helles Bock this afternoon.
They are easy to transport and share. I like that about them. As long as you take care of them they'll last a long time.
(I haven't done this yet, but) my only GRIPE is the price. They are between $11-15 on-line to my local HBS.
I got all of mine from Germany, FULL OF GERMAN BEER for less than $10.00! None of that EXPORT stuff. The REAL stuff - UNPASTEURIZED!
Anywho, that's my opinion. Your mileage may vary.
As far as cleaning...just like bottles...rinse them out when they're empty and you'll never have to scrub them...
...rinse them out with the jet bottle washer that's all.