Yeah I don't know how it compares with other cameras, but mine appear to be fine, you can individually set the sensitivity for each cam, which I've done.
A good price for the adequate Pro 720p versions. However, I'd invest in Pro 2 1080p versions if your budget can stretch (or you can wait for a deal).
I wouldn't make a judgement based on a forum where people go to complain! You look up any forum on a product and it shows similar. The Arlo comments on that link are worldwide, from reading a handful it all looks like internet lag causing problems. If I go to a Samsung S10 plus forum it's all complaints about how rubbish it is and this and that doesnt work.... I've owned my from new and all perfect. My arlo is 2yrs old, never an issue. We all get good and bad with whatever we buy, but to link a community is obviously just going to be full of complaints. Dont get me wrong, helpful, and be mindful, I just couldn't make a decision based on a community forum.
before anyone buys this i would suggest you check out the Arlo owners forum and then make up your own mind. https://community.arlo.com/t5/Arlo-Pro/bd-p/en-arlo-pro
Following the deal link to the product page says this is used stock. In this case customer returns that are complete.