I have heard good and bad things, and we ultimately decided that we're just not going to be spending enough to make it worthwhile.
The people I know who have good things to say spent big bucks there, and put the breakeven point around 30-35K (and keep in mind, that is materials/furnishings only, not labor - I think a lot of people go in thinking about the savings in relation to their total budget, not just the materials cost). That's not a hard number to hit if you're building a house, as our friends were, but it isn't a deal for the typical remodel or redecorating project as the commercials make it out to be.
I know we're not going to be spending anywhere near that much on materials, appliances, and furniture, and I am far to particular about my ideas to buy into something without seeing exactly what they have to offer first. I dragged DH to 4 tile showrooms before I found the mosaics for my half-bath! So we decided it wasn't for us.