You can cast this spell only once per level, and a limited number of times in your life. You must have most of the corpse available to cast the spell. There's no time limit on resurrecting a dead PC, so long as you have the corpse.
You can bring a creature back to life in more or less normal condition, with varying levels of recovery.
Limited Casting: The first time in your life that you use the spell, you can cast it with a single standard action. Using the spell removes one of your spell slots until you gain a level. (You get one less spell per full heal-up.) The person you are resurrecting comes back at roughly half strength, e.g. expending half their recoveries, being dazed (save ends), and, for each ability, having a 50% chance that it is expended.
The second time in your life you cast the spell, it takes at least three or four rounds and costs you roughly half your hit points and daily powers/spells. The person you are resurrecting comes back at something like one-quarter strength.
The third time you cast the spell it has to be as a ritual. The spell chews you up and leaves you with only a few hit points, then gnaws at the person you have resurrected, who takes days to recover well enough to qualify as an adventurer or combatant.
The fourth time you cast the spell it nearly kills you. The resurrection succeeds but the person you've resurrected is going to be a mess for a month or more, regardless of any other magic you use.
The fifth time you resurrect someone, that's the end of your story and you die. There's only a 50% chance that the resurrection spell works on the target. You've used up your quota of resurrection magic. You're not coming back via this spell, either.
Limited Resurrection: If the target of your resurrection spell has been resurrected more times than you have cast the spell, there is a 50% chance that the experience will play out using their higher number of resurrections instead of the number of times you have cast the spell.