Arlo is a re-brand of Netgear, which was purchased from Avaak Vue.
In terms of how long the batteries will last, specs say "4 to 6 months". However, this is for motion only recording assuming a fairly low number of events. So you can't record continuously and, if you have a busy area, battery life can be significantly lower than that.
While being 100% wire free is a great aspiration, the limitations it requires to achieve that, are fairly significant.
Can't say much about the current product as it's been a couple of years since I looked at Avaak in depth. But back then it was very in depth..
As John points out, the use cases are quite narrow.
The concept is convenient and effective as a point solution where you need to temporarily deploy cameras to keep an eye on something. I.e. going on vacation, keeping an eye on your kitchen remodel, etc.
Setup is easy. Quality is okay. Worth the price? Depends on how much is at stake in these use cases and how often they occur.
One unexpected benefit of 100% wireless is that you tend to find camera positioning can usually be optimized or changed completely after you live with a particular view for a while. These types of cameras are often moved after they're initially deployed. Something that's not practical with wired cameras.
But in general, unless you're actively monitoring a camera system, they tend to fall into disuse after the initial newness wears off. So if you haven't looked at these in a while, don't be surprised if they're not working when you eventually get around to them--due to battery failure, the camera got disturbed, or (possibly--although I don't know this to be a problem) the wireless got wedged.