That is a very subjective question since $25 could be chump change to some, while it could be grocery money to get through the week for others. Looks at it this way: If you only use it on M13, you are playing around 42% of what the retail game costs to get the game early. However, if you use it to download other games early, you are paying $5/game for a three day rental. You also have to consider how much time you will get with the game in those three days. It may be more worth it to someone who can clear their schedule for the weekend, while other people who can't get off work or have a spouse and kids might not want to drop money for something they will only get an hour a night with the game (not to mention a wife wondering why you paid $25 for a game that you already paid $60 for that you're getting on Tuesday).
It's up to you to decide whether it's worth it or not.