This feature is completely awesome. I just went through all my wilds that I caught over the course of the game, and I figured out the IVs for all males with one of the 6 comments that would be indicative of a potential perfect stat. Look at all these things with 31s that will be very helpful for breeding that, in RSE, I never would have known about (like hell I'm taking every Pokemon I own to the IV man who is way out of the way in the first place). I ignored females because they can only make offspring of their own specie which I felt was pretty limiting, and I'm a lazy guy. There's a good chance that I have a female or so with a perfect IV, but I'm fairly apathetic about them:
Kricketot(bug): defense
Machop(humanshape): speed
Starly(flying): special defense *also a 30 in speed*
Wurmple(bug): HP
Dialaga(no eggs): special defense *yeah, I know*
Anorith(water 3): HP
Shroomish(fairy/plant): HP *EDIT*
Ditto(ditto): special attack *timid/native DP too*
Yeah, I already knew about the Ditto having 31 special attack before this, but I had to throw him in for bragging purposes. I didn't bother to check his offspring, many of which have mischievous as their description, because I know many of them probably have a 31 special attack. Okay, even ignoring my beloved Ditto which will parent many, many special sweepers over its lifetime, most of the rest of these are really noteworthy as they're a great potential way to start breeding within their egg groups for those Pokemon who couldn't care less about special attack. Also, the marking feature has been expanded to six marks. I used this to my advantage by marking all 31 IV Pokemon with a mark corresponding to the IV they have maxed. I would highly, highly suggest that everyone go through all the random wilds they got throughout the game and do as I did and use the marking feature to keep track of them. Why breed forever to get a random 31 when you could have one through more basic heredity from a Pokemon you already own?
I'm 100% convinced that this feature knocks the socks off the IV man because I can quickly use it in the menu and because it's so specific. Sadly, I don't have anything with 2 perfect IVs so I couldn't check how priority on that is handled, but it does at least help you narrow down Pokemon. If you're a really dedicated breeder, you would instantly ignore anything that didn't have one of those six phrases as it has no perfect IVs. Any of you master breeders from RSE who have multiple perfect IV Pokemon could do us all a great service by transferring to DP and checking what the description is. I doubt it's random, and it will probably either favor the top of the stat list or the bottom (so something perfect in everything will, if my theory is right, have either "Often dozes off" or "Alert to sounds"). Knowing how that works would really help breeders get the most out of this surprisingly awesome feature.
Also, as I wrote all that and remembered the other thread "what to do in Emerald", I was thinking that we probably have enough experts to make a really awesome DP breeding guide. It would certainly give people who are new to Pokemon but serious about doing it well a very good reason to come here above everywhere else.