The JotW nerf makes the Ret numbers pretty interesting. Let's start by defining some terms for PvE:
- Basic Rotation: Seal, Judgement, Crusader Strike, Divine Storm, Divine Plea (use all when cooldowns are up)
- Burn Rotation: Basic Rotation + Hammer of Wrath
- Minor Spells: Flash of Light, Hand spells, Avenging Wrath, Hammer of Justice, Exorcism, Repentance
- Major Spells: Consecration, Holy Light
Unbuffed, a Ret paladin can sustain the Basic Rotation forever. However, any other spells cast come out of her mana bar.
(This assumes that the paladin takes Benediction and the Crusader Strike glyph. The Crusader Strike glyph is pretty much the second-best glyph now.)
Raid-buffed, a Ret paladin can sustain the Basic Rotation plus about 1 Minor Spell every 20 seconds.
The Burn Rotation, on the other hand, can only be sustained for one minute. After that, the paladin will be out of mana. Any Major spells cast, or extra Minor spells, further reduce the amount of time the paladin can stay in Burn mode.
Essentially, a ret paladin will stick to the Basic Rotation all the time--maybe tossing one or two Minor spells every so often--while maintaining 100% mana, until the boss drops to 20% health. Then the Ret paladin switches to Burn mode, and has one minute to kill the boss or run dry.
The largest effect of the JotW nerf is to ensure that the Ret paladin will almost never cast Major spells like Consecration or Holy Light.
Honestly, I don't think it's that bad a scheme (for PvE, anyways). I've never really liked Consecrate being part of the regular rotation. It's an AoE spell, and should be reserved for AoE situations.