silky smooth but clanky like a cow
This thing feeds cord like water. The belays are super smooth as are the rappels. I love that you can belay two seconds with this device and it will automatically lock on one or both of the ropes.
Two things I don't like about it are it's bulk (compared to an ATC for example) and the *clang clang clang* ruckus it makes when clipped to your belay loop while you are climbing.
I prefer to use it on long trad routes in parties of three or greater, but for anything else I still haven't found a replacement for the ATC.