In my opinion you never know until you try. But I will be surprised if it works any better. As an extender it uses WiFi to talk to your router. This will not magically get a better WiFi signal than your devices get so I am fairly sure service will remain spotty. This device can also be setup as an access point in which case if you have an ethernet cable run from your router to the upstairs, you plug that cable into this device and that would give you better coverage upstairs since the cable provides the connection to your internet. If running a cable is not practical for you, I would give a power line network extender a try. I have never used one, but I hear they are fairly good providing you have a good electrical system in the house. With this type of device it uses your household electrical wiring to send your data between two devices. One will be upstairs and the other down by your router. Best buy has a NETGEAR - Powerline AC1200 Gigabit Ethernet Adapter (2-pack) - White that is highly rated. But I don't think this provides a WiFi signal so you would still need a WiFi device to send that signal out. You could use this and the Extender you are asking about, cable the two together and be all set.
NETGEAR - Powerline AC1200 Gigabit Ethernet Adapter (2-pack) - White
(2,405)
NETGEAR - AC1200 Dual-Band Wi-Fi Range Extender - White
(5,470)