I installed it with polyurethane glue (Elmers) on a base of 3/4" birch / maple plywood, that had additional 3/4" pine support struts underneath. Once in place we use epoxy grout to seal the very thin (1/16" or less) joints. Everything has held solid - no cracking, shifting, etc. The grout has no stains and looks as good when installed (my DW cooks everyday).
While not being full slab, the tiles are large enough to only require a few joints. The island top shown is 90" long. I believe it's a good trade-off for doing granite at $25 per square foot. That being said, I don't think this is a project for a novice or new DIY'er. If you have a fair amount of experience with tile or masonry, it's not too bad.