A friend asked about that one just the other day. My very limited education says it seems OK. My qualifications don't quite rise to Holiday Inn Express, more like I stayed at a Motel 6.
I recently bought a refurb Flir One Pro. I like it but the phone connection part is less than ideal. I bought an older USB mini version since it was $250 vs $400 for new with USB-C. I can use it with my older phone or, via an adapter, with my current phone. I'm considering getting a USB C extension cable so I don't have to worry about a simple knock, drop breaking the connector.
Turning the thing on is a bit of a hassle since you have to power up the phone and app (since this isn't my normal phone I keep it off). You also have to power up the device as it has it's own battery. I wish it was powered off the phone but nope.
Anyway, based on my research it seems like phone based is the best option in terms of image and features for a low price. Data capture is a easy since I can send pictures from my phone. However, the trade off is you have to deal with a clunky setup. I wouldn't hand it over to my wife and expect she would figure it out. Conversely, an all in one unit should be easier to operate for basic stuff but you have to use a memory card to transfer pictures.
Also, mine has the dual camera setup where you can blend the heat map with a photo to help you understand what you are looking at. That Klien doesn't have that feature. I don't see that as an issue when you are looking at the image and the real object. It might be an issue if you are looking at saved pictures.
Since I'm less concerned about complexity during use (or for others), care about cost quite a bit since this is largely a toy for me, and field use durability isn't a concern I favor the phone based models. I might change my mind if I had to put this in my toolbox every day. It would be nice to handle these things before buying.