Flat pannel TVs just don't put up the money for quality speakers. I have friends that tell me they can't hear the diff, and I have friends that tell me that they agree, the soundbar was a great buy.
As much as it pains me to say this:
Go a bit more expensive and buy from Best Buy (*cringe*), or other box store near you so you can easily return it if you fall in the "sounds the same to me" category.
Just make sure you do a real test - blue ray movie will obviously make it sound significantly better - by trying what you'd mainly want it for. Watching "The Price is Right" won't have much of a noticeable difference, whereas a high quality football game will make a bigger one, and movies/games even more-so.
I have one (retails for $599, got it on sale for about $250) hooked up to an especially thin LED display (speakers are complete crap, and may as well be not included to reduce weight), so I love mine. I have heard mixed things about the sub-$100 ones tho.