If you're a paid game, you're going to have a very hard time getting sales, because you can't acquire users. The 99 cent 'race to the bottom' also means you need a lot of sales, but it's tough to achieve that today without a brand or big-name. Even Apple featuring you doesn't add up to as much as it used to.
So, you might have noticed a pattern amongst the more successful freemium titles. Lots of wait timers, short gameplay bursts, unlimited purchasables, etc... what hardcore gamers deem as evil, is actually what these companies have determined is the most optimal way to make money. I'm not trying to be depressing here lol, but before you make the decision to go free, make sure you understand what you're up against. I personally hope we can head to a more League of Legends type model where you make $5 on a lot of people rather than the Farmville route of making $5000 on a few 'whales'. I personally much prefer a great game that lets me pay when I'm ready to invest, than a game that is trying to milk me the whole time.
Just an FYI, me and a friend built Stratosphere: Multiplayer Defense for iPad and have gone through much of this dilemma lol. Good luck!