Painfully slow and hogs the entire system. Activity monitor has it running CPU67% in the background all the time. It will import NUTD calendar beautifully, but it's just not usable and so slow you wonder if it's actually doing something. I wish they would, at least, make some small fix that would allow NUTD (which I love) be able to simply synch with an iPhone without all the bloat. I will give it 2 stars because, after importing the NUTD calendar, it allows you to spit out an .ics file (though I don't use iCal).