I also tried the marathon and half "extras" the first year they were offered. I certainly agree with 10nis that I did not get my money's worth out of it. As Denny said, I found I missed the interaction with my Disney Dead and WISH friends, so pre-race I didn't stay that long in the tent. As a huge fan of cool weather, the warm tent was no draw for me, but the promised character greetings were. As it turned out, I saw Donald only after the full (no characters were around during my tent time for the half). Also, I was told I'd need to wait 50 minutes post-race for my free massage. I waited about a half-hour before giving up and walking massage-less back to the busses. (Maybe if I'd been faster, the wait might have been shorter.)
Having said that, I'm glad I tried it once, but I definitely won't do it again. I'd prefer to splurge on a spa treatment at the Grand Floridian or Saratoga Springs -- or even at Canyon Ranch Spa at the Gaylord Palms. Just my opinion, though.
EDIT: OH! Forgot to say -- And I'm trying the eat-and-greet again this year. I went to a similar pre-race dinner several years ago (then Disney changed everything and it really stunk), but this year's advertisement made it sound much more like what they used to do -- with character photo ops etc. The price was not out of line with other character meals and I'll be there with other runners and their families. I'm hoping it will be fun.