Yeah, for the most part, it is a great way to level out the playing feild, and we do the same for our domestic league(MLS). Only problem is that it hurts if you have to play teams from other nations who don't have a salary cap and can spend wildly like certain teams in the Premier League or La Liga... If they were forced to share the best "draft" picks and had a salary cap, then the Premier League would be very competitive and exhibit a lot more parity. Not sure how you would tweak it for the relegated/promoted teams though (also a trait of european leagues that is non-existent in MLS).
Luckily, the NFL doesn't have any competitors outside of the U.S. so the salary cap and draft are a way to encourage parity in the league and really keeps the league interesting every year, because each team has a chance to win the "Super Bowl" every few years.
Part of the reason I support foreign leagues rather than the domestic league is because of the salary cap and the potential for European trophies. It's just more interesting seeing teams all over Europe compete against each other.
Because of the cap in the U.S., the MLS will never be able to afford a Ronaldo or Messi-esque player... until they are way past their playing prime like T. Henry and Beckham.
Getting every one in Europe to agree to a world-wide salary cap would definitely be wild, but the leagues in Brazil and Argentina would probably rule the planet since they generally have the best homegrown talent. Then again, tactics are a major concern as well.
Sorry about the rant... just a little aside!