It depends upon what you're looking for.
It's a decent sized TV at a good price, but at that price point, I'd probably buy a 50" Hisense instead and get a decent 5 yr warranty with it.
Undoubtedly though it's a poor quality TV made by Vestel in Turkey or by Foxconn and will not be up to watching 4K HDR content on. It will be fine-ish for HD content if you're not fussy.
The UI could be a bit ropey, probably laggy, however your Firestick will take care of a lot of that.
If you want a decent 55" 4K TV for HDR content, you're looking at ~£1k for the last of the 2019 TV models (Sony XG9505) or another £500+ for a 2020 model.
While the 2020 models may be currently overpriced, you can see why a £329 TV isn't going to live up to the standards of a £1500+ one.