From what I have read, I don't think sound bars are nearly as effective as discrete speakers for surround sound, but I suspect they are far better than alternatives such as Bose systems. The link below goes to a June 2008 article by Audioholics on sound bars. At the bottom of the article are references to other articles including the Yamaha YSP-4000, Yamaha YSP-1000, Samsung HT-X810 and Niro Nakamichi 1000 surround bar. You can read them and get a feeling for what sound bars can and can't do.
http://www.audioholics.com/education/loudspeaker-basics/sound-bars-silicon-chip-ti/?searchterm=soundbars
I haven't read all the references thoroughly yet but I think sound bars may be better for surround sound than a pair of wall-hung stereo speakers for a flat screen TV, and they are probably a lot less trouble and cost than running wires to 5 or 7 speakers around the room. I could see them being a low cost installation option if you are having the system installed by an installer (such as for older parents and grandparents.)
As noted before, you still need a subwoofer and there may be room-shape requirements for proper operation. I also think the sound bars look esthetically clean and sharp installed, especially where the sound bar length is close to the width of the flat panel TV. I could see one of these for an appartment or for the WAF and it may be acceptable sound quality wise and even for surround sound. I base a lot of this on the review of the first Yamaha sound bar, which was apparently done correctly concerning steering of the sound fields. Just putting a bunch of speakers in a sound bar without the sophistocated sound steering behind it probably is just basic sound and mostly appearance.
