Don't know about "hate" but the reactions that I'm reading are completely unsurprising to me.
I've tested Photone twice and, after trading email with the programmer, would recommend Photone only under very specific circumstances. The first time I tested Photone was against a blurple running Photone (then called "Korona") on my iPhone XS Max. Even though I was using the required light setting, Photone failed to give a reading. I
I got in touch with programmer (I've been a software engineer for over 30 years, including three years for Apple, so I'm more than comfortable discussing programming), and we discussed the app and some of the issues that he's trying to work around. On an iPhone, Photone
may be accurate, but, according to the person who wrote the application, there are significant obstacles to getting an accurate combination on Android. the issue is that there are so many different Android devices that it's very,very difficult to write software that compensates for the limitations of dozens and dozens and dozens of sensors that are used in android devices.
For people who insist on using Photone, it's probably accurate if you have one of the devices which growlightmeter.com has tested. If it's not one of those double "chosen few double ", calibrate it, using something like an apogee, or by using a third-party PFD map against your light. You can also use manufacturers PFD maps, but…it would not surprise me if those values did not accurately reflect real world conditions.
Rather than spend money on an inexpensive PAR meter, most of which are in capable of detecting light with a frequency higher than 660 nm, I would just go with the Uni-T Bluetooth, light meter, and use the document that I've attached to convert the luxe reading that the Uni-T is giving you for your light into a PPFD value.
In the past week or so, I've seen grow journals where the grower is using Photone and the readings that they're getting for PFD have been obviously out of line. When I tested Photone the second time, it was reading 16% high across all dimmer settings. All three of the growers who have reported their Photone readings have been getting PPFD values that are significantly high.
Again, Photone can be used successfully. The problem is that unless you compare it to a known good source or it's one of the specific devices that growlightmeter.com has tested, then you simply have no idea how much light is hitting your plant.