This is exactly what we did this year. I recommend it if you want to get a full-blown trust and/or you have something atypical in your will.
We've been happy with the attorney we've found through them. You do have to pick from a list, but wills & trusts is mostly a "forms" based legal practice. It's important, but it isn't rocket science.
If you just need a simple will, you could find a better deal with online services or template programs. I previously used Quicken Willmaker, and it did what we needed.