Welcome, my name is Rick and I will do my best to help you with your issue
As long as the deck is properly prepped this product is a good option for older decks. It's the same product as Rustoleum's Restore.
I need a bit more information. What exact prepping is required?
The surface must be clean (no dirt, oil, grease) any peeling finishes must be removed. Here is a video that gives you a product and application overview. http://www.youtube.com/watch?v=TijxWmM-yBcAs with any paint finish the prep is key to a satisfactory outcome. Any bad feedback you hear is usually a case of poor prep.
You can undo your premature poor rating by rating me favorably now.