They are a joy to use. Although I was apprehensive at first like you, I find shifting with bar ends really natural. The left shifter (for your chain rings) will be friction and you do it mostly be feel. This works extremely well because you have near infinite control over your trimming and can make micro adjustments. The right shifter can be set to either index (clicking) or friction shifting. I usually just leave it in indexed mode unless I'm having some kind of cable adjustment issue. You move it between indexed and friction by turning the little D-ring on the left side of it.
Hope this helps.