I own two Flow Hives and I mostly agree with the above post.
I bought my first one direct from their crowd funding campaign, but I sold that when I almost gave up. Then bought again - a discounted one from their website and the next one was second hand - some one bought one and never opened the box.
Short story: they do work with some caveats and make extraction easier and less messy. But if I had to start again with the knowledge I now have, I would not buy again.
Long story: I am very disappointed with their workmanship and quality control. I have a shed load of parts that had to be replaced or repaired - leaking roofs, brood and super boxes that were poorly machined, queen excluders that fail within a year, bottom boards poorly assembled that I had to try and fix, and pretty much every Flow frame came with incorrect wire tension resulting in honey leaks. I went through a few disastrous honey leaks, flooding the brood chamber. Another Flow frame had to be replaced entirely because it was defective. Quality control is shockingly poor though others weren’t as unlucky as me apparently. To make up for it, their customer service is responsive and generally replace stuff. One super had to be replaced three times, which is mind-blowing. No wonder they cost so much, they have to cover the costs of all the replacements.
Try to find some genuine reviews and you struggle. On their own website, they only publish the 5 star reviews last time I checked. I left a 3-star review myself after the super debacle that had to be replaced three times, and they never published that. I also have very strong suspicions that they enter into agreements with celebrity beekeepers, giving them free hives for the exchange of glowing reviews and endors. Recently I also saw some other celebrities like David Beckham featured assembling a Flow Hive on UK papers - obviously a marketing stunt. This annoys me.
Their save the bees mantra and marketing seem to target naive world-saving-do-gooders with good intentions and zero beekeeping experience, and not enough understanding of what it takes to keep and manage bees long term. To their credit they are now encouraging taking beekeeping courses and are monetising that themselves by selling online courses. But still if you look at their website it still largely looks like a really easy gig - plop a beehive in the backyard and turn a tap for honey. Just had a look at the aussie website - there are photos of young girls with a lot of exposed skin harvesting honey from hives which are obviously misleadingly bee-less (you can see that from the lack of bees on the honey frames seen through the open side windows. It is deceiving marketing and annoys me no end. Their claim that you do not disturb the bees is bull crap and grossly misleading.
Also, check the prices of the individual components and compare with your local bee store. Excluding the plastic flow frames themselves, some standard Langstroth Flow branded parts are between twice and four times the price of regular kit, especially when including the unavoidable postage.
Then on the other side of the story, I recently joined their online forum and although I found it boring and not very active, there are people that are obviously happy with their purchase. Personally I started out liking the hives and the company ethos behind them but over the years I grew more sceptical.
People will keep buying them as long as they keep up their cunning marketing plan.