I have two Otto's and they're doing great. They immediating starting sucking tank glass, and haven't stopped since. My tank was established with plenty of algae and they have quite an appetite, however, they poop frequently. It's funny though, everyone talks about how they cleaned their tanks of brown algae and my tank still has plenty of it on my driftwood, plastic plants and such. It's not such a big deal since I didn't purchase them to clean it out.
You can easily wipe the algae off ornaments and I read somewhere that it grows in new tanks.