I actually like flying Icelandair.(My boyfriend laughs at me when I say that)
I have taken several flights from Boston. I thought the seats were comfortable and I also thought the meals were pretty good (as far as airline food goes) There is not as much room as there is on American, but I am pretty short, so that was not a problem for me.
I have never stayed longer than a few hours in Iceland, but I would love to, so if you get the chance for a stopover there...I would suggest it.