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It seems fine. Connection is pretty solid (although it does seem to struggle a bit when I leave my house and the wi-fi is disconnecting, I suspect that's a problem with the phone though) and sound quality is OK (it uses AptxX which isn't available on every phone). Certainly does the job for £20.
I've not really used it with decent headphones though so couldn't comment definitely on how it performs in a decent setup. I read reports that it's a bit underpowered for driving bigger headphones but I've no plans on using it for that.
There are quite a range of Fiio ones between that price and the Radsone one you linked, not really sure how they all compare. The BTR3 is meant to be the best I think but not tried it.
In my hunt for headphones with a short cable I ended up buying a short cable with MMCX connectors and these earphones to go with them (about £30 all in).
They sound OK but lack a bit of bass and the sound isolation is poor so thought I'd try some different tips, maybe some triple flange or foam ones. How do I work out what tips would fit them? The tube at the end seems to be ~ 5mm.