For my use case, I’m happy with the ‘Top-up’ method.
Basically, I have the Curve Black card, which I got for free as a promotion (usually £50, and it’s 100% not worth that price right now). I’m an Amex Cashback everyday card user, which I got just before the beta (I was holding off because I mainly used my curve card).
The top up is limited to £1000 a month (30 day rolling, not calendar month), and I’ve just hit it. If I were to top up anymore I’d be charged the 0.65%, so I’m not going to do that as I’ll just use the AMEX card itself if I need to.
The biggest annoyance for me is that it doesn’t pass through transaction details like it does for every other card. So there is a promotion starting 1st December, which gives you £5 back on a £10+ spend at select places. In this case, I will just have to use the Amex card. Little annoying but I’m okay with that.
The main thing people are complaining about is the Curve Blue users always having to pay 0.65%, which if I was a Curve Blue user would put me off 100%. And also not being able to withdraw cash from the Amex Wallet in curve, but again for me that’s fine due to having a Tandem card which through Curve is no fees cash withdrawal.
TLDR; For my use case I’m happy despite the many issues/downfalls etc. Don’t join Curve for it, don’t pay for Curve Black, don’t use it on Curve Blue. But if, like me, you’re happy with the shortcomings then it’s really nice having all your cards in one physical card (which might soon support Apple Pay).