Is that the one that has an built-in cell for recharging? I've got to admit I know next to nothing about the Streamlight range of lights, so it's nice to hear some good feedback. 
Yes, the battery stays in the flashlight, but if you want to change it out, it comes out, just like a regular flashlight battery. The replacement batteries are about $20, but I hear they last a long time (years). I chose this one because buying the CR123 batteries are not an option (I don't like buying batteries). I am going to buy a couple extra rechargeable batteries for backup. I believe the brightness of this little light is 160 lumens, and it's noticeable. The cradle is the best I have seen for a rechargeable light. I bought a couple od belt clip "ripoff" holsters for carry, and those are working out well too.