I have a Galco ankle holster and I find it reasonably comfortable. The issue I have with ankle holsters is that they slide down my ankle and become unconfortable and exposed.
However, since I prefer to wear short boots (just above the ankle) I find that the top of the boot stops the ankle holster's downward slide. Galcos also come with a strap the goes around the upper calf, just under the knee, and attaches to the holster to keep it up. I don't like that so much - I feel it too much.
My preference in my "ankle" gun also helps. I carry a S&W model 340, .38 spcl. +P, AL frame with Titanium cylinder. The thing only weighs 11 oz; a bit more loaded.
Then we need to remember that carrying a gun will never be as comfortable as not carrying a gun, but not carrying a gun will never be as comforting as carrying a gun.