Are there any special considerations when buying a security camera?

I use the Blink cameras inside and outside of my house. They came in real handy when my husband was in a hospital bed in our living room, and I had to run an errand, as I could easily check on him through my smart phone anywhere I was. I could also hear him on it, which was nice as well. Now mine are the older models, as the newer ones, now have 2 way talk, which is even better, as you can not only hear your mom, but talk to her through them as well.
So I think the 2 way talk should be a definite consideration.