They're great candidates for life, especially given mounting ideas on the origin of life possibly being tied up with geochemistry and geology.
They're lousy candidates for big biospheres that utterly transform the geochemistry such that you could see it far away like ours has, or for complex life, since the total energy flux available in potentially clement environments is miniscule compared to here. But Earth's biosphere had to start with something a lot like the energy sources you have in the icy moons, not photosynthesis.
This is the first in a series of posts I am putting together on a personal blog I just started two days ago as a collection of my musings on astrobiology ("The Great A'Tuin" - sorry, I couldn't help it), and will be reposting here. Much has been written here about the Fermi paradox and the 'great filter'. It seems to me that going back to a somewhat more basic level of astronomy and astrobiology is extremely informative to these questions, and so this is what I will be doing. The bloggery is intended for a slightly more general audience than this site (hence much of the content of the introduction) but I think it will be of interest. Many of the points I will be making are ones I have touched on in previous comments here, but hope to explore in more detail.
This post references my first two posts - an introduction, and a discussion of our apparent position in space and time in the universe. The blog posts may be found at:
http://thegreatatuin.blogspot.com/2015/07/whats-all-this-about.html
http://thegreatatuin.blogspot.com/2015/07/space-and-time.htm