The Enigma Order

I was asked few times whether haste was any good for hunters, both by mains and alts.

The real answer is - I don't know. The way I see things, haste should be rather godly after patch 3.0. As I see it, a hunter benefits from it twofolds - it reduces the time between autoattacks and it decreases the cast time of steady shot. Those two factor together with autoshot clipping removed results in a rather simplistic equasion: more haste=everything being shot faster. One thing I'm still unsure aout is how GCD impacts this - in theory, a hunter should never (never-ever!) be able toto autoshot faster than every 1,5 sec. However, in practice, I'm quite sure that its perfectly possible (herosim, rapid fire, aspect proc, haste pot, meta gem proc and you're easily down to 0,7 ish attack speed as a BM with 2.8 attack speed weapon) - so far I haven't been able to check whether the shots are shot according to the char pane attack speed (every 0,7 sec orso) or according to GCD (every 1,5 sec), but I could have sworn it's the first option.

As for armor penetration, it's a bit of the other way round - as I understand it got nerfed in patch 3.0. This is becasuse pre-patch it was calculated as a value of the armor of a mob which was being ignored. Say - your 300 armor pen resulted in 500 armor being ignored on a mob (numbers are out of the blue). The more armor pen you had, the higher the multiplier went, hence the better it was getting (ex. if 300 armor pen meant 500 armor being ignored, than 600 armor pen meant not 1000 (500x2), but 1100 (more than 500x2)). This was all applied after raid wide debufs such as Sunder Armor and Fiery Fire.
As it is now, your armor pen is calculated as a percentage of the amount of armor a mob has. And it's being calcualted after raid wide debuffs. Hence, if your personal armor pen ignores 10% of mobs'a armor, than - again simplistic calcualtion - a mob will 10.000 armor will be accounted as if he had 9.000 armor as long as you're soloing (lets say this is 10% dps boost). In raid, effects like Sunder Armor and Fiery Fire have priority, lets say that they take away 2.000 armor away, your 10% armor pen than applies to 7.500, resulting in 750 armor being ignored, as opposed to 1.000 while soloing (thus a 7,5% dos boost rather than 10%).
The above would mean that the the more armor a mob has, the better armor pen is (which, again, wasn't the case pre-patch).
Also, I belive that the multiplication effect ("2x500>1000") was removed, but I'm not sure about that.

That said, even if we agree that armor pen actually did got nerfed, it is still a very decent characteristic.