So I have had a look at the "free to play" option for Star Wars: The Old Republic. The following things are restricted unless either you are a subscriber, or you're willing to shell out money for "Cartel Coins":
-full experience gain for questing
-full access to gear rewards for questing
-full access to race choices for your classes
-ability to hide your helmet
-ability to display titles
-ability to display legacy names
-ability to unify colors of your outfits
-having more than two characters for your ENTIRE ACCOUNT
-doing more than three Flashpoints (dungeons) a week
-doing more than three Warzones (PvP) a week
-doing Operations (raids), period
-accessing new content (Section X/HK-51, etc.)
The list goes on. Yes, you can play it for free, except one, you still gotta buy it (i.e. Guild Wars), and two...what's the friggin' point? Yes, you can level your character to 1-50 and do the storyline without restrictions (except for the reduced XP gain and gear choices), but what then? People complain that STO is "pay to win", but STO doesn't restrict you to only three STFs a week, and doesn't make you pay to do New Romulus, for instance. Imagine if it did. The outcry would be huge.
My verdict: Honestly, if you're even remotely interested in this game at all, try it free, and if you like it and want an unrestricted gameplay experience, subscribe. Just don't be surprised if it folds like EA's other MMO based in a popular universe - Warhammer Online.