Best Amazon purchase I've made in a while! I'm guessing people who have left a negative review are either expecting way too much for the money, don't understand the limitations of RF technology, or maybe received a lemon.
I've used these regularly for over two months and they have helped me find my keys, wallet and remote control countless times.
I have small children, in particular an 18 month old baby girl who likes to take and hide all of Mommy's stuff. It's too soon to know for sure about battery life, but I will say that between the number of times my daughter has given me occasion to search for things (with it taking an average of 6-10 "button pushes" to locate the item), and both her and big brother (age 5) playing with the remote and pushing it just for fun - I would give this high marks for battery life because the remote and all fobs are still fully operational. The replacement batteries are also much cheaper now than they used to be, so the expense to benefit ratio is already quite reasonable.
This also speaks to durability, because kids are hard on stuff. Furthermore, I've dropped my keys (with attached fob) on concrete, and dropped the remote on hard floors, and everything still works. The key fobs have even survived a quick dunk in both water and coffee (yes, thank you, baby!).
Given the very reasonable price, the durability, and the battery life so far, this is a 5 star product that has literally saved my time and sanity many times. I'm going to buy another set of the newer rechargeable ones because you can never have too many (would it be wrong to put them in my kids?), so it will be interesting to compare,because newer isn't always better.