the 10-29 bracket will be ill-suited to prepare you for the 30-54 bracket (kiddie pool is very shallow, grown up one is too deep.)
Just to add my thought here, I don't think a pool that people eventually level out of is bad wrt the "kiddie/grown-up" thing. The problem is when a pool is stagnant by having people staying in it indefinitely. In WAR, things got so bad through the lack of a bolster system and an escalating gear ladder that it drove me into suggesting retiring characters at some point to generate churn. Anyway, people who are good at PvP and who play it a lot, or at least frequently, will go through their brackets relatively quickly (with 30-54 potentially taking a few weeks for the more casual players, and far longer for real casuals), so that "excessively good" players will hopefully be more of a novelty than a nuisance.
I for one find the 10–49 bracket right now far more fun than the 50 pool, even when I was running my 20-something against decked out late-40s freak groups, and a good place to learn about the basics of your character. With the upcoming 30–54, some people may not get to learn about their capstone skills too much before that, but it has a very good chance of presenting a better progression than the current "what the f▇▇▊ just happened" shellshock you inevitably get when entering your first level 50 warzone.
In that vein, IMO free2play players should get a few more warzones on their weekly allowance