In terms of the detail, I used to do very detailed breakdowns of categories, but now I don't really see the point: my app supports 'split transactions' (one of the reasons I actually made it, as existing solutions had poor support for them back in 2009), and I generally just use things like 'Food', 'Drinks', 'Essentials' as categories, as it never really made sense (at least for me) to detail them with such accuracy.
But for things like 'coffee', I do 'Drinks:Coffee', so I can see how much I am spending on fairly specific things, but I guess it's a balance in terms of whether it's worth the effort to record them so accurately compared to making use of the details.
Similarly, things like 'Car:Fuel', 'Car:Service', etc...