We've got the j groove style of handleless doors in our kitchen and while I like the clean look, the true handleless style looks even better (though it's expensive as the manufacture is more complicated).
Some dirt does get caught in the grooves, but it's not as dramatic as the above poster makes it out to be.
Opening the dishwasher and in particular the fridge and freezer was a bit of a pain, but used to that now.
Hate the J-handle things. Can't fit my fingers in it properly, when i do they get caught, can twist, sometimes slip out. Like you said a pain to open certain things.
Just ripping out our 18 month Pronorm (rad pipe upstairs went and flooded the kitchen/units) and putting in a Leicht handless one in the summer. Will get a build thread up.