I have used IF for a while now, and I eat every day. I once went a full day (waking to sleeping) without eating to see what it was like, and (no surprise) it was shitty. Anyone who suggests or claims to do that regularly has no interest in building muscle.
I've eaten pretty low-carb for the last few years, but I don't know if that has anything to do with the way I've reacted to IF. Basically, I'll fast for 18-24 hours once or twice a week, going entirely by feel. Sometimes it's unplanned (no time for breakfast today, guess I'll fast) but usually I do it on purpose and intentionally eat more than normal before starting. Then I'll stop eating after lunch and not start again until breakfast (~20 hours) or lunch (~24 hours) the next day. If I skip breakfast, I'll have three or four meals by the time I go to bed, and if I know I'm fasting in the evening, I'll have three meals in the morning, usually.
The key, for me, is that it's always controlled. I never binge on junk after a fast just because I'm hungry, and I also never fast so long that I only eat 1000 calories in a day. I try to keep my calories pretty consistent day to day, just moving them to the morning or afternoon as appropriate.
I have to say that I like it a lot. Since I've started, my back, shoulders and arms have all gotten bigger and my legs have, at worst, not gotten smaller, while I've been cutting fat. I haven't had any trouble working out fasted, either, since I've gotten used to it, though I mostly workout fed. I do like doing a sprint workout or some other type of HIIT before I break my fast, but I've had some great "real" workouts fasted as well.
I started doing it because I was curious, really, and I won't stop unless I find that I can't put on any more muscle, which doesn't feel like it'll happen anytime soon. I wouldn't recommend it to everyone, but if you're curious, it can work if you're reasonable about it. The iflife link posted earlier is, in fact, pretty good.