I have both my mom's and my results at FTDNA, as well as my brother's yDNA and Family Finder results. Is it worth it? Oh, yes - ABSOLUTELY. At FTDNA, you get a chromosome browser so you can see exactly on which chromosome and segment you match. You can also download your matches and their matching segments, the chromosome, the locations and the length, so if you're good with a spreadsheet, the information you can pull from this alone is well worth the $69. You can also filter matches in a variety of ways: in common with a different match of yours, or not in common with another match, surname, the name of the person who took the test. You get a few strong matches at the same segment, then you are all cousins. Also, there is a utility that lets you copy your match's tree (if they have one) and save it as a gedcom.
I found 4 good, strong matches to my brother and me and they don't match my mom. So they have to match my dad. He was adopted and I'm trying to locate his birth family. I pulled down their trees from FTDNA and started what I call my Paternal Chrome 18 tree at Ancestry. I'm researching each of their lines, adding marriages and children and cousins. If and when I find a common ancestor between these four trees, I can be almost certain to have found an ancestor of my father, and then ultimately, his birth parents.
Once I find his birth family, it is my intent to bust down a couple of my mom's brick walls and help a couple of folks that I've matched to find their ancestors, too. I have enough research goals to keep me busy for years. And at FTDNA, it's a one time fee - never a membership.