I have somewhere around 14 of the Blink XT, XT2, and mini cameras set up on 3 different Blink modules, 2 of the older ones and one of the Sync Module 2s that has the option to use a USB stick for a recording set up, two are exterior cameras and one is for inside the house. I've had them for a couple of years now and these are my thoughts:
The Blink cameras represent a pretty good value. The ability to place them where ever you want is one of the biggest draws.
You need decent WiFi to run them, I'm using a Google WiFi mesh and my farthest camera is located inside my shed about 250' from the nearest router without issue.
Cameras in "high traffic areas" are going to burn through batteries. Cameras in low traffic areas live up to the reported battery life. You can run alkaline batteries but it's not worth it.
The biggest issue with them is the "reset" time. If it detects motion and it stops, there's a delay in another recording. Thus adding multiple cameras.
You can get different mounts that provide more flexibility in mounting, don't get the ones that the case screws together, they are a giant PITA to swap batteries.
The ability to divide them into different systems is nice, I disarm the interior cameras when we are home and turn them off when we are gone.
This winter I will probably run a USB hub in the attic to power some of the high traffic areas to decrease the amount of lithium batteries I'm using. I've not tired to use rechargable ones yet. Connecting them to USB does improve their ability to record longer I believe.
I've not had any issues with them being exposed to the elements or other longevity issues with them, I've accidentally hit a couple with the pressure washer and dropped them trying to change the batteries.