Extended Stay is a great concept, marred by poor quality control. Our stay was a mixed bag, but I'll try them again on the hope their quality control improves.
The great concept is that every room has a full kitchen (minus conventional oven), so that if you're staying awhile and don't mind cooking a bit you can eat your own food - improving quality and saving a butt-load of money.
Our problem was that the first room we were given was uninhabitable - missing a major furniture item, light out by the bedside, phone not working (couldn't reach the desk), pillows minus pillow cases and one of them stained with a bit of blood.
A second room was fine, but of course we had to move to it. The desk help was super-friendly and helpful, so I can't fault that, but clearly their QC and room inventory were sub-par.
Still, once we got settled we were happy with the place, and will give them another shot.