I picked up Metal before going to Turkey since my UK bank charges stupidly high fees for any international payment. I would've paid more in fees than the cost of buying bread. Back then Metal was much cheaper, so it wasn't so bad. It was only recently they increased the prices and removed cashback and introduced air miles.
If I wasn't still in a foreign country I'd ditch it. Their savings accounts pay a good 4.5% on GBP which is quite high and paid daily which is another decent addition. But yeah, if you aren't travelling a lot then Metal is just a waste of money per month.