Well a month in, a few thoughts.
First off, this is a life changer for me. As someone who just buys whatever he wants all the time and then wonders how many nectar points he has on his nectar card at the end of the month, this has changed my life. I can't budget for shit, never have, so I put a bit on it every week and that's my budget. It's really forced me to think about every penny I spend and I've got loads of money now oddly.
As for the card itself, I've yet to find a place where it's not accepted or doesn't work. Topping up is instant and transactions appear instantly and I get a notification on my phone every time I spend any money. My only issue which is in no way Starling's fault, is that TFL doesn't charge me instantly for my travel, but rather calculates it later on due to capping. So it'll reserve a 10p fee when I enter a tube station and then a few days later hit me with the rest. It's not a big issue, it's just something I need to be mindful of.
The app is fantastic and extremely intuitive. I haven't even explored all the features and only looked at the basic stuff but it's blown me away.
The uses this has is immense. If you have kids and want to give them pocket money, this is perfect. I'm yet to suss out how this company makes any money but I don't really care.
Honestly if you suck with money then you need one of these. @crispymorgan I apologise for taking the piss. Saving money is fucking awesome (will still take piss though).