Very good question, thanks!
Our objective is for you to not need to manually correct any transaction, we use the information of the card network (MasterCard currently) together with our own database (where we store every merchant we encounter) to give you enriched info, emoji, map, logo and category. The more users we have and more stores you visit the better we’ll get.
In practice, there are always cases where that’s simply not enough and we’re going to fail 
From merchants where you can buy radically different products (you can go to Sainsbury’s and get a £50 iTunes top up card) to small merchants that get to share the same point of sale for different businesses (barber shop / phone unlocking, etc.) and even other payments players, as PayPal, where you can pay lots of different things but in our side we only see “PayPal”.
Very soon we’re going to start working on Your spending and I’m sure we’ll learn a lot about how to minimise the pain when the categories are wrong.
On the radar, of course, things like integrating with big merchants to get to know exactly the items you bought or even get access to your email to scrap your Amazon purchases and things like that. But that’ll take time 