Playing with the fingers takes a lot of practice, rather than plucking the strings the way you would on a guitar it's more like you 'caress' the strings, letting them more or less 'roll' out from under your fingertip. It's tough to describe, but once you get it to happen a couple of times you'll understand. Digging in to the strings is more of an effect for most styles of playing. To hear a good range of string attack and the difference it makes in the sound, take a close listen to Rio by Duran Duran. It has everything from light caresses to sharp snaps. Not really my favorite band but a very well-played song and fun to cover.