The BOSS Blues Driver has been around for a while. I like this pedal a lot. It does not sound like your typical TS-9 pedal; instead it is very transparent without the same strong midhump as the tube screamers. You can use it in several ways - solo boost, rhythm playing or lead playing.
My Blues Driver has been modified by Steve Dudley, and makes it a little smoother sounding and less harsh. Some people find the BD-2 harsh sounding, and it's a good idea to keep the tone knob below 12 o'clock. I find the Blues Driver to be a great pedal for getting your tube amp just that little extra drive, withouth changing the tone. Fender players seem to really like the BD-2. My single-coil guitars really like the Blues Driver.
If you start with a good amp tone, stepping on the BD-2 gives you a great tone for leads. It has a bit of a trebly sound, and I find it is best to keep the tone knob down a bit and the same goes for the drive knob.
It can also work as a booster pedal - by keeping the gain low and turning up the volume knob a bit, you get a significant volume boost without any changes to your overall tone.
The Blues Driver is one of the best OD type pedals I have ever encountered, and it's definitely worth its price tag by far. Using it right, it can be that desert island pedal!
If you have to go to a deserted island for a while, be sure to bring with you the BOSS Blues Driver BD-2. Together with a decent clean sounding tube amp, there is no need to be bored while trying to survive in the sticks. This pedal gives you all you need for blues and rock, and it will last you a lifetime.