Nothing is ever easy!Follow

Actually leveling is pretty easy now days. Only have to jump hoops for the limit breaks but you should be able to find people willing to help with that.

Having recently went through this, I'd like to list the terribleness that you must endure for this free play time:

Can't /tell unless that character has sent you one first
Can't /shout
Can't /yell
Can't trade
Can't buy or sell in bazaars
Can't use the AH
Can't use the dbox
Can't invite anyone, regardless if they've sent you tells, friend invites, etc. This is a killer in GoV parties where you randomly get the lead and there's lots of unresponsive/afk people
Can't enter any expansion areas, including Zilart
Annoying symbol next to your name that guarantees at least 5 tells a day asking what it is. On the bright side, you now have 5 more people you can send tells!

In the end though, getting lvl 30 War, Mnk, Thf, Whm, Blm, Rdm, Pld, Rng, and Drk, subs, as well as some progress in rank missions, and a little gil isn't so bad, for free play time. Pop those brown chests in Gusgen, you'll never be so happy to see Ogre gear and Elixers ever again.

I didn't think you could unlock advanced jobs on a trial account, but seeing as there's only three of them you can possibly get to without expansions that's not far from the truth.

Tell you what's nice though: Fire up a trial account, level to 10, use as sync target to grind out Amorph and Plantoid trials in newbie zones.

Too much of a hassle to do anything else on it. Having no way to get items or gil to or from a trial account is the biggest killer.