I'm a Barclays man too, so I just set it up with my Amex instead.
Again I really cannot see the advantage of using your watch over your phone, it might save a second, or two. My life is really not so busy I cant get my phone out.
Or the advantage over a contactless credit/debit/Oyster card for that matter. Especially in the example of the London Underground...
I just don't "get" it either.
I used apple pay on the tube last weekend, it was amazeballz.
BUT I'm not a London regular, so it only saved me queuing behind 300 chinese students at the ticket machine. This scenario is obviously a very limited use case
However, the oyster thing is on the right, and I wear my watch on the left, so I just used my phone and thumbprint to applepay. It worked quickly and felt futuristic. If I was a London regular I wouldn't bother with an oyster card now, the phone was dead easy to use and one less thing in my wallet and never needs topping up. However, using it on my left handed watch would be a minor exercise in contortion
You can just use your contactless debit card too - I go into london all the time and just use that - no extra or less hassle than using a phone.
Contactless is good, but I do find it easier to get my phone out than a contactless card as they're in my wallet, also my Amex isn't contactless and I use it the most because it has the best benefits. Obviously that's not the same for everyone though. I wouldn't suggest for a minute that it's best for everyone, but it's a very quick and easy way for me to pay. Given the absence of security on contactless cards, I would now prefer none of mine to be contactless and simply use my phone which requires my fingerprint.