I bought these cameras primarily to use as a test device for work. I needed something that had an ethernet interface and worked as an IP based device. I found them on eBay for around $20 each. I bought two cameras, the model IPC-3605N and the model IPC-4605N. The devices run basically the same hardware it seems, with the IPC-4605N having pan, tilt, & zoom capability.
I generally enjoy figuring out if embedded devices are well built or simply cobbled together, so I spent some time looking at these devices.
TLDR - Do not buy, do not use, and remove all of these devices from service immediately. They are so miserably insecure it took me less than a day of effort to develop a utility to remotely compromise any of them. Keep reading if you want to know how.Hacking Zyxel IP cameras to gain a root shell
Rascals are always sociable, and the chief sign that a man has any nobility in his character is the little pleasure he takes in others company. Arthur Schopenhauer