I'm giving this a three chiefly because of the frustrating setup. 'no configuration' it isn't. 'Push a couple of buttons and you are done', nope. Took two hours. However, once up and running it seems to work pretty well.
So what happened? There are two sets of 'quick installation' instructions with the kit, which is a little confusing. Spending some time, it became clear that one set was only about setting up a wired connection, the other for wired and wireless. The whole point for me was to extend the wireless network, so I took that one, but not after first doing the other one. I plugged the small adaptor into the wall socket near the router, plugged the ethernet cable between the two, went upstairs and plugged the larger (wi-fi extender) box into a socket upstairs. I got the impression that it would pair up automatically, and perhaps it would, but in fact I did the 2-second button press on both anyway, and they paired just fine. So far, a five star effort.
Next, read the other quick installation guide, where it says to plug the wi-fi extender close to the wi-fi router, press the WPS button on the router for 2 seconds, then the button on the front of the extender (not the little pairing button underneath) for 2 seconds, and watch the pretty lights. I watched the demo on youtube, but it never did what the youtube video showed, the lights just never did that, it did the fast flashing straight away, not slow flashing for twenty seconds, then a little fandango and finally fast flashing. I tried this multiple times, and also did the reset (little hole underneath) and tried again. Nothing. It always showed as a separate wi-fi network called 'TP-Link...', which I couldn't log into. It definitely wasn't copying the SSID and password from the router.
Check the PDF manual online. You don't get this manual with the device, nor a reference to it, I think. You do get a cd-rom, but it is one of the mini ones that only work with tray-loading dvd drives, so useless. OK, so I learn that the extender has a web interface. It says if you are connected wirelessly you can go to http://tplinkplclogin.net but I couldn't connect via wireless. I plugged in my Macbook Pro over ethernet, but that address didn't work. I noted that it gave me an IP address of 192.168.1.67 so I tried entering 192.168.1.1 in the browser, and got a password dialog. Entered 'admin' for both and got in. In there, I set the SSID and password manually to match my router, rebooted, and no it worked!
Now it is up I like it, but I can imagine a lot of people getting very frustrated setting it up.
UPDATE: I was finding that although my Macbook pro and all the iPads could connect easily to the router as before, my iPhone would not even see the network, but if I took it upstairs would connect happily to the extender. Also, the Mac upstairs (which is more or less equidistant between the router and the extender) would keep dropping its connection. A family member's Dell would not see the network at all and had to use ethernet. This was with them sharing SSID and channel to make a seamless wifi zone. So I made the channels different, channel 1 on the extender and channel 11 on the router itself (still sharing same SSID and password), and now it all works fine, everything can connect everywhere. I searched on the web for info about channel settings, but it was ambiguous.