We use them quite a bit, have three for different areas. We do a ton of soft tissue work at the end of sessions and/or off-days.
I was at an expo yesterday for endurance sports and the stick had a nice informational booth. They told me I needed the strongest one, so I got one for me, and one for my brother. I rolled out my vastus medialis (been having some pain there while squatting, into the groin area), and today I have some nice nickel to quarter size bruises.
I was never able to get to these places with the foam roller. Further, the stick is better on the hamstrings, I feel.