When I saw the announcement about this ova a few months ago I was pretty excited. A What-If story where Shinichi never got his old body back sounds very interesting if you are a fan of the Anime/Manga after all. So I started watching it, expecting an adult version of Conan (along with his friends) getting caught up in another case like we are used to from the manga or anime. After all this serie isn't called " 'Detective' Conan" for nothing, right? Wrong! Instead we get a 7 min explanation of why we are going to seeing all the characters 10 years older with Conan, Ranand the others still being their normal age.
These 7 min could have been better spend, especially considering that the ova is only 23-25 minutes long.

Okay, after these boring first minutes we get to see the adult Conan followed by an appearance of nearly every other closely involved character with around 1-3 min screen-time. Doesn't sound like much, but believe me when I say that this is more than enough, seeing as the only thing that was changed were their age.

Usually you would expect at least a little change in personality over 10(!) years but all of them are the same and only look older. It's okay by those like Kogoro but why the hell are Ayumi, Genta and Mitsuhiko still acting like when they were 8 years olds?
Maybe I'm the only one who thinks so or it was just that we only saw them for a short time, but that was how I saw it.

Taking this into account and the whole set up of this so-called "What-If"(because for me a what-if is when you show how a character progressed in an alternate way than originally planned) I have to say that this OVA has absolutely no point.

Despite the lacking story or any kind of development the Art and Design of all the adult (or older) versions were actually rather believable.

So, all in all if you have the urge to see what Ayumi or Genta or any other characters would look like 10 years later go google a picture, takes less time and brings the same results.