This device (hardware revision V2) is quite solid in its general performance (strong signal reception, good speed), but when coupled with an unreliable (ADB) router and an ADSL line (special thanks to the biggest Croatian ISP!), it gave me a lot of problems with the internet connection on various clients (using various OS versions, from Windows, over the Windows Phone and Android to Apple iOS). Basically, it would(n't) work intermittently.
Nothing could be found from the system log, but it seemed like it had a problem with multiple (approx. >5) clients connected to it and that's why I've decided to give it a second life with a firmware upgrade. My assumption was confirmed by the manufacturer, stating the following (marked in yellow):
The upgrade procedure itself is fairly simple - upload the file by using the Web configuration GUI and just remember to do it by using a cable (LAN) connection.
After the (successful) upgrade you should get a message pictured below:
However, even after the firmware upgrade and the router replacement (for a Siemens SX 763), this extender wouldn't work reliably without its DHCP enabled (and manually set - without any overlapping with the root AP's DHCP, of course - along with the DNS server values).
Also, there are obviously some other software glitches (for example, after the configuration backup to a file, upon restore it simply wouldn't work as it should before the backup / restore procedure - and there weren't any other changes made to the network meanwile).
All in all, I'd call it (only) a good product, obviously flawed by some firmware-related bugs. If you're looking for an easy-to-use extender, I'd certainly recommend the D-Link DAP-1320 over this one...