re: Wifi Range Extenders - Worth it?

I haven't tried a range extender like the one you linked, so I can't speak specifically to that. I did, however, try a powerline adapter. It's a similar end-goal, but a different way to get there.

All that to say, the powerline adapter was a total waste of money. T-O-T-A-L waste.

I mention that only because I investigated the same thing you are, and my research brought up powerline adapters as well and they seemed like a great solution. False.

I ended up just getting a more powerful router.

EDIT: As mentioned above, a powerline adapter could be a good solution in certain houses and wiring systems - but it does heavily depend on the wiring in your apartment/house.