WDS can indeed lower your setup costs if you are running an office. The low cost of the router and access points makes for a highly attractive option instead of running cables everywhere. Of course, many office spaces are already wired, so there may be times when this does not apply. However, while a WDS system is a money saver, it also has a few limitations and obstacles to overcome.
Setup can be lengthy and problematic (if times or settings are not identical). Bandwidth is limited on any system connected to the outer nodes and there is no set standard for WDS, meaning you take your chances when you buy products supporting this. Of course there are rumblings that WDS will be standardized and adopted by the WiFi Alliance in the form of 802.11s in the near future (say 2011), but until then it is still up in the air.
For the home, WDS is sort of a mixed bag. It is true that it was able to do almost everything we asked of it (with the exception of online gaming), but at times it did bog down when running multiple streams (or gaming while someone else was watching HD video). While we cannot speak for every WDS enabled router or AP, we can say that the configuration we tested from TRENDNet was quite nice and for the most part easy to setup.
Our final thought is that WDS is getting there. If you are looking for a low cost (and secure) method to setup a business network in an area that is not pre-wired, then WDS is a great option for you. If on the other hand you are looking for a home network that maintains high speed and bandwidth for all of your connected systems, then you may want to stick with a single extended range wireless router or opt for a powerline system for now.
We will be following up on WDS as it matures, though, as after our experience with it we feel it certainly bears watching.