I don't rate it as useless. Many users on this forum rely in it, and although I mainly use powerline networking for mine, I spent several months trialling the Edimax dongle and alpha-testing the WebIF extension to configure it for my impossible-to-enter-on-the-SUI WiFi credentials.
I've had nothing but trouble with the wifi on four different HDR Fox T2s, failing to connect to the wifi automatically, bandwidth so poor I couldn't stream anything including iPlayer SD, and on some occasions the entire HDR Fox T2 needing a power cycle. The Edimax dongle with the hi gain antenna is merely bad, the Humax dongle is worse than useless in my experience.
To solve all this, I managed to get cabled ethernet to my two boxes via a gigabit switch behind the hifi. This requires a 5m drop lead (to feed the switch) that I haven't quite managed to hide to my satisfaction everywhere, but at least it works.
At my parents I ran some Cat6 under the floor between my dad's study (where the broadband router is) to a socket on the floor behind the TV rack. And for my parents' HD Fox T2 upstairs (remote client), I had to run some more Cat6 (external grade) under the floor, through the house external wall to go up the wall outside (and this is 18 feet in the air due to the lie of the land, huge ladders needed), back in through the house wall and into the dormer bedroom under eaves space to reach a socket on the wall. I assure you if the wifi worked to a usable degree I would not have gone to this much trouble at my parents. And it's not wifi congestion, I can only see one other wifi network at my parents.
Which leaves my aunt's where I thought wifi would be enough to run a standalone non networked HDR Fox T2, since all I need it for is occasional maintenance. Apparently not, even this is too much for the HDR Fox T2's crappy wifi. I have ordered a TP-LINK TP-WR702N thanks to Black Hole's suggestion, this will be configured specifically for the task and then left at my aunt's house so I can use it to manage the HDR Fox T2. With luck it will join the hotspot my iPad Air2 creates, freeing up an iPad3 for anything I can think of to use it for.