I do it every once in a while. I do okay with the foam roller, but I saw a lot more improvement with the inclusion of mobility WOD.
I don't do crossfit, but I noticed a really big difference in how I walk and lift with the MWOD. If you decide to do it, go back to the beginning and start there. It hurts, it's not necessarily fun, but the difference is worth it.
I got the recommendation for lacrosse balls as sort of a weird foam roller hack from MWOD, and they work better for small areas. I still pull out the foam roller when I need to hit a bigger spot, or go to see my a.r.t. specialist when it's really bad.
If you can afford it (or insurance covers it), I'd suggest going to see an A.R.T. specialist. It basically re-works how you move your muscles, and fixes any movement issues. Think of a full body muscle movement with the benefits of a foam roller. Between the MWOD stuff and a.r.t., I feel a lot better than I did before. No shoulder mobility issues, no carpal tunnel pain, and my i.t. band and calves aren't tight, so I can walk and stand correctly.
Conclusion? I like foam rollers, but I do better with a lot of different things than simply one tool. Foam rolling is a tool, there's more in the box, and I like it, I just don't find it to be the end-all fixit tool that some trainers or people find it to be.