I've just dropped down to 12mg nicotine and it's much nicer!
I'm using 12 myself now and aim to go to 6 in their week or so. I used 24 for a long time before changing to 18 for a while and then 12. I didn't notice much difference each time if I'm honest and I hope to try 6mg for a while before giving it up completely.
I've found vaping to be a completely different animal to cigarettes after I got used to it as if I go out somewhere and forget my ecig it's a minor inconvenience whereas when I smoked if had forgot my tobacco I was a panic stricken gibbering wreck incapable of anything very much until I could have a smoke again.