This pedal if of course fantastic. It is more or less a factory standard for pedalboards all over the world. A volume pedal is so simple in its construction and components, but can make a lot of difference for your sound, tone and mannerism. You can of course use it to simply regulate your volume, but you can also use it to shape your overdrive tone or do fantastic ambient volume swells.
A volume pedal is a must on my pedalboard and the Ernie Ball VP-JR really lived up to my high expectations.
A word of coution: Make sure that you buy the correct one. There are different versions depending on your guitar pickups. I have not experienced any of the infamous "tone suck" but I am not using the tuner out, just to be sure to get the most "tone" out of my setup.