I've not driven one like this (thankfully) but I've heard a colleague of mine complaining about them on a new Astra he test drove. he said he kept indicating left when trying to turn the right indicator off and vice-versa not just annoying,bloody dangerous if you ask me.
My SEAT ibiza has proper latching indicator stalk but it also has the "flick" feature where if you flick it up or down it will indicate three times in that direction. Useful for changing lanes but bloody annoying and possibly dangerous if you flick it by accident as the only way to stop it before the 3 flashes is to indicate the other way!!