The TL-DR is, i've only used this paired to my watch for almost 2 years with no issues, and I get good quality data. I haven't used it stand alone, or paired to the Flow App on my phone to record sessions.
I have been happily using my verity sense HR band for almost 2 years now paired with my Polar (grit x pro) watch. I've also used it with my Polar Pacer Pro. In that time I've tracked just under 6,000 miles of running HR data and a lot of hours of strength training, mobility, and bike riding. I've had two bad readings in that time and both were my fault.
Over all I'd say this is great value for money. The strap adjusts to my skinny runners arms, and it can get pretty long too for huge forearms. I'm a heavy user of this device and i'm a fitness professional who runs and works out every day.
I came back to look at this device as I was thinking of getting another one for my wife, and a new strap for my sensor. I'm still on the original strap, and its holding up very well. If you are looking at the low star reviews, then I can see most are for people using the strap with their phone or some other cardio equipment. I've never tried that so I cant comment on that use case.
I've compared the Verity Sense to my H10 and it's pretty close, I've also got a really good feel for my HR levels so I know its giving me good data, if it didn't then I'd not use it as wrong data is much worse than no data.
I don't have much success with the optical HR data on the watches, as it tends to lock to my cadence from time to time. The Verity Sense is placed just below the elbow joint on my forearm and seems to work very well there. As usual with all optical HR sensors, there's a 15-30 second lag, so don't plan to use it for accurate readings while doing short intervals. That is where you need the H10 or other ECG device.
Battery life is good. I get somewhere around 20-ish hours over a week of use.
Now that Polar have the loop band I also use that for all day wear, and take it off when I'm using my Polar watch and Verity Sense combo, between the two I get HR (and lots of other data) readings 24/7 with no noticeable drops.
Hope this helps with your choice.

Picked up this HRM to replace my Peloton branded HRM. I only use it w/Peloton (bike, tread and app). It works flawlessly every time! HRM have shrunk in size over the years (YAY!) and this one is no exception. Fits great, I feel the readings are accurate, connects quickly w/Peloton and the battery life seems to last forever. I've also used this while hiking and camping. The durability can't be beat. Afterall, it's Polar! Oh, and the color? Anything besides your boring black is a win in my book.