I tried one and I didn't like it. There was no additional EQ and the BT sound streams pretty flat. So if you go for one, try to find one that either has EQ settings or a good rating for natural sound quality.
I tried the Bose Soundlink at my local VZW store and was very impressed by it. While demoing a sound-system in such an open and loud environment is far from ideal, it performed well enough that I'm giving it serious consideration.
To MrSmith's point, streaming over bluetooth has inherent issues, but as for eq there are several apps in the maket place that will help compensate for the lack of settings in a speaker.
I have these speakers which also include rechargeable batteries that last 10 hours, imo they sound pretty good (high's & lows) and positive user reviews (majority). The price can't be beat.
I heard the one made by Jawbone and I was impressed with the quality and sound range as well as a nice small package. At $199 believe Jawbone was pretty impressed with it also.