It really doesnt affect anything unless you are trying to get into the back seat in which case you duck under it and once you are in the back seat it doesnt affect you at all. It one of the best looking mods for a vert IMO.
Tip: Take off you seat belt guides the plastic things your seatbelt goes through after puting a lightbar in or else those will jack up the sides of your lightbar.
They aren't very burdensome, but i've hit my head on mine a couple times adjusting my seat. With me and seat fully set back, I don't hit my head, but come close, if you're taller than 6'2" you might have problems.
I have had a few people hit their heads on mine, but thats just their stupidity getting in and out. Also, tall dudes in the back can easily hit their heads when you brake hard if they aren't paying attention.
Only complaints I get are from the brake light being fairly bright since I don't have the cutoff switch for when the top is up lol.