This product is OK, however please be aware that when it describes fitting 12 pairs of shoes this does not include trainers.
In addition, a slim fitting pair of shoes would fit one of the cubby spaces so long as the shoes are stored on their side and in the top-to-toe position. This can be a problem if the soles of your shoes are the slightest bit dirty.
You can store 6 pairs of shoes very comfortably (including trainers) if you only put one shoe in one cubby space, not two.
If you want something that can store your trainers, shoes, flip flops etc, a proper shoe rack would be much much better.
On the plus side it is a very compact product and looks nice.