I just downloaded it's pretty neat and clever. It's a mentalist feat that utilizes a very basic mentalism principle. I have no idea why a reviewer would call this trick "Stupid". I wish he'd clarify more. Even aside from the effect itself, the principle you learn is awesome and you can use it to get your creative juices flowing. You'll need a bit of audience management as you don't want them messing with your stuff.

One note, though the trick is free, you'll need a standard card gaff. You'll find out what it is as soon as you order. This effect also works with the newer bicycle card case only, but it's fairly standard now anyway so it shouldn't pose as a problem.

I thought this was a trick where you had to spell the number or something like that. But it is not like that. The thinking behind it is pretty devious. Also, it is free, so just get it!

Okay, so this isn't a perfect trick. But it's a wonderful idea, and can be customized as you see fit.
There are multiple outs here, one of which is very strong, two of which are somewhat weak, and two of which are strong but a bit tricky. (I'm referring to the card box.)
An easy enhancement to make the trick stronger: have a single examinable card in the card box, and another card reversed in the pack. You can then dump out a single examinable card from the box (strong and easy) or spread the deck for a strong reveal.
There are many other possibilities as well. "The Fine Print" by Jay Sankey has an Ace of Spades with tiny print saying "I know you will pick the Queen of Hearts!", which could easily be placed at the top of the deck and even forced if necessary.
"The Big Finish" has a powerful whammy where four cards form a jumbo King of Hearts.
I have an "Astor Card Frame" gimmick (which is fantastic, btw) in which a Jack of Hearts appears, but can transform into any card on the way out (for instance, the 10 of hearts, to make that revelation stronger.)
Possibilities are endless. You could use "Monkey in the Middle" to produce their selected card in a sandwich, etc. If each reveal is equally strong, you won't be disappointed that they picked a particular selection.
Bravo, Oliver, for a wonderful idea at a great price, and for inspiring our creativity.
You are a gift to the magic community!

Good job. I'm not sure I'd use the db in the card box, but that's a preference. Not sure why one reviewer was so negative. These type of effect have been around for a long because they can quite effective. As long as you make the final reveal strong and seem the only one possible.

Many use only three or four items, so the thinking on 5 is good. I used carry one around in my pocket for years that only had three cards. Each reveal was clean in view the the whole time, and looked like it was only prediction.

Magic is about learning and adapting principles. That's what Dan Harden is doing with the Tarbell course.
Keep at it.

I did not personally get much out of this, but if you are just starting out in magic or mentalism, this is definitely worth taking a look at. And it's free, so you can't complain. If you have been into magic or mentalism for a while you might not learn a lot, but it's just a quick pdf file anyways, so it is worth giving a shot. All in all, a good product.