They're OK - good for decent vocal processing on a budget. Better than what you'll get in most mixers, but far below the more expensive Digitech and TC Helicon units. They sport a good mic pre, reverbs and delays as well as phantom power and workable highpass filters, EQ and compression. i.e. everything you really need to get a decent vocal part.
Harmonies are a weak point IMO (especially by latest generation standards - take a look at the
TC VoiceLive 3) as they offer only preprogrammed keys and intervals (rather than the follow-along modes of the other brands). So there are times you're going to get the wrong harmonies (i.e. you can't do Beatles-style fourths and you'll run into problems with the V of minor keys).
