Originally Posted by Voxx

Technically, haste increases rage generation, decreases Flurry uptime (under the same idea that slower weapons = higher Flurry uptime) and has no effect on PPM mechanics.

Crit increases Flurry uptime, increases rage generation (in a spiky way however) and also has no effect on PPM.

Things to note about both:
Crit is always at least a 100% increase on damage for that swing (more with Impale and RED)
Haste is guaranteed extra damage, the extra attack gained from 1% Haste is subject to the entire attack table and therefore could be a glancing, or a miss, or alternately could be a crit.

Haste affects all of your white damage, none of your instant attack damage, and a minor effect on Heroic Strike (due to increased rage generation) damage unless you have enough rage to Heroic Strike every mainhand swing. Giving a very rough estimate, I'd guess it affects around 40% of your damage, with an additional 1% of your Heroic Strike damage for every 1% of Haste. I.e 1% Haste should average to around 1% more rage generated long-term, therefore 1% more Heroic Strikes.

Crit affects all of your damage that isn't already a crit, excluding the 25% of your white damage that is glancing. This should be something like 50% of your damage(?) assuming 40% is from white damage and you have a 40% crit chance.

The way I see it, crit has a slightly higher value than Haste, and affects slightly more of your damage than Haste, however it comes at a higher cost. 22 rating vs 16 rating. I'm too tired right now to try and actually validate any of the above or to go into any further detail and thus there's a good chance that most of the above is blatantly wrong. I'll sleep on it.