We've had this discussion here so many times. All the negatives people list are 100% accurate, yes.
I'm in two leagues that draft like this, before the NFL Draft. Would I want all my leagues to do this? No, it introduces more luck into the equation. But I have 4 other more standard leagues, so it's fun to have something different.
The high point of the year, moreso even than in normal leagues, is the rookie draft. It may slightly hurt the value of mid-late 1sts but it significantly helps the value of lottery ticket picks later on. Like the poster above, we do 7 rounds (non-IDP) and have deep rosters.
Does someone occasionally draft Carroo or Da'Rick Rogers way too high? Yeah, and we all chat and point fingers about it as the NFL Draft is ongoing, it's a blast. It comes with the territory and leads to people having fierce loyalty to "their guys". Is that how I play in my other leagues? Not at all, but it's different and fun. And you can also get some total steals if you do your homework and have their names on your radar before anyone else. Knowing who John Brown is, liking him, and taking him in the 6th before the Steelers surprisingly draft him in the 3rd round and make people take notice is a sweet feeling.
It's not for everyone and I wouldn't want all my leagues to do it--but it's fun and its a challenge.