I think the biggest knock on vff's is that they don't fit everyone.
.... and for that reason, I
hate my VFFs. (I got them free for running on the Lieberman treadmill.) For me, the VFFs have provided 10 new place to get blisters. I'm barefoot on roads, but will wear other minimalist shoes on trails and in the snow. I usually run road races barefoot unless it's super cold.
The whole barefoot versus VFF dynamic at races is a bit weird. I don't typically chat up the VFF wearers on my own, since I'm usually just trying to survive the corral (I'm short and get squished a lot). Sometimes, people in regular trainers will try to chat up the VFF wearers, and then it gets all awkward if they see me. Conversation typically goes like this:
Shod runner: So, how are you liking those VFFs?
VFF guy: They are great! I'm really tough because I run with no cushion, but they offer the protection I need for my soles.
Shod runner: Oh, hey - there's a barefoot girl! Doesn't that hurt your feet? Don't you need some protection?
Me: No, they are fine. See?
Shod runner: So, why don't you wear VFFs?
Me: I'm sorry, but why should I?
Shod runner: Don't your soles need protection?
Me: No, see? They are fine. I've run about 40 miles this week barefoot, and no problems.
Shod runner: So, VFF guy, why don't you run barefoot then?
VFF Guy: Uh, well, I, uh, glass?
Shod runner: Yeah, how often have you stepped on glass?
Me: It's not really a big deal. I've never had to miss a run because I stepped on glass.
And VFF guy is getting all embarrassed because I'm this mousy looking little lady and I don't need that "protection".