Welcome to Beemaster.
From reports I have read, it is a really good design.
Most of the negative comes from the fact that it attracts people that no nothing about bees to buy one and expect everything to work.
It is not the flow hive. It is the lack of experience of thousands of new beeks with no knowledge thinking they can buy it and have honey pouring out of it.
I recommend you get a hive first and learn how to keep bees first.
This is a great site for learning about bees.
Bee careful, beekeeping is very addictive.