I find them extremely useful, altho I don't alway use them - sometimes because it doesn't fit the RP I'm doing and sometimes because they make things a little too easy.
OTOH I have mods that make having them around a much better experience than it was in the vanilla game, altho the mods don't change their combat AI as far as I can tell they do give me more options with followers and that makes their little quirks and flaws far more tolerable.
As for them getting in the way, a lot depends on your combat style vs the follower's combat style.