Not playing it yet... but I like the minor tweaks made in the new rules. I also like the convenience and quality of getting the bound versions.
I've purchased all three books currently released through Mongoose, primarily for nostalgia's sake. Our group might give the actual rules a go sometime after one of our two 4e campaigns ends, but in the meantime I'm certainly mining the books for ideas. There's a ton of good campaign meat in the main rulebook (the Lands of Legend, medieval setting info, grittier Old English theme) that's just as useful for a 4e D&D campaign. Plus, the adventures in Sleeping Gods have some excellent atmosphere, and are readily converted to other systems.
I'm looking forward to future releases, particularly any "new" material that comes out for the system. My only complaint so far is the quality of a couple of the maps in Sleeping Gods. The full-page maps are excellent, but the smaller maps are hazy and difficult to read. Would be nice if this could be corrected before The Elven Crystals comes out.