In all the theorycraft for Holy paladins I've seen so far, everyone automatically values Haste above Critical Strike chance. I'm not really sure I follow this logic.
Haste improves your Healing-Per-Second (HpS). But it also hurts your Mana-Spent-Per-Second (MpS), and does not change your Healing-Per-Mana (HpM). Crit, on the other hand, improves your HpS and HpM, but does not change your MpS, at least not directly.
Right now, it seems to me that the real limit on healing is mana. Therefore we should be valuing stats which improve HpM above all else.
It's true that you can't count on crit in the short term, but you can count on it in the long run. In the current environment, one heal isn't enough to restore someone to full health. In that environment, crit helps a lot. It buys you time, and allows you to get away with casting less spells. If you need three casts to bring someone up to full, and one of the first two spells crit, maybe you don't need to cast that third spell.
If you need high HpS, that's Flash of Light and Divine Light are for. Haste was awesome for the world when you absolutely need the heal to hit right now or the tank dies. But I find that I don't really encounter that situation, at least in heroics. Or if it's close to that, Holy Shock, Word of Glory, and Flash of Light are fast enough already.
What I've found in heroics is that I really, really want to see spells crit. A crit spell usually means that I don't have to cast a follow-up spell on that target, and I can move onto the next target in triage faster.
So that's my view on crit versus haste. As of right now, I think I'd rather take crit gear over haste gear. I just don't think the advantages of haste gear are of real value in the current healing environment.
A couple of caveats, though. I haven't tried any raids, so I don't know if this changes. Second, this is just haste versus crit. Spirit is still the best secondary stat, while I think the jury is still deliberating over Mastery.