I have it. It's noticeably more responsive than Firefox, but much
bulkier in comparison; especially with certain (larger) pages when I try to scroll them, as other apps will want to quit right then.
One
issue is, that IceCatMobile fails to show its own user agent string,
and uses a UA string of non-free software, which skews server
statistics. I had to guesstimate the possible IceCat UA string for
myself.
The good thing, though, is that I can have a custom UA string for some sites that would otherwise display badly.
-M.