Just gives you a coin bonus when you start up MUT for the first time.
I'd recommend going through the skills trainer in the game for anyone who hasn't done that. You get players for each one you get a gold medal in. The cards are all pretty much low rated versions of superstars and legends, but they can still provide some depth if you're not too far along with your team yet.
Also, the first coin-up of the season is up. Ravens vs Broncos. Ray Rice or Demaryius Thomas. For those unfamiliar, there is a solo challenge against the Ravens and one against the Broncos. You get coins and a Demaryius Thomas card that you can either hold onto, or immediately put into a collection to receive the Ray Rice card. You choose the card you keep based on whoever you think is going to score more TDs in tomorrow night's game...and you get something like 2,000 coins for every TD they score.
These coin-ups were the most addictive part of MUT last year for me, and almost started to feel like gambling. I only stopped doing them because the rest of the mode was such a grind, it just didn't feel like they were helping that much. Hopefully that won't be the case this year.