Personally I have 3 kills and no weaps. My alts are going going to /suicide if this freaking weap doesn't drop soon.
I hate how this was miscommunicated by GC/Blizz, they gave us the impression that it was going to be a guaranteed drop and I was oh so happy... Then I realized he meant that it was guaranteed for your MS *when* the god damn thing drops, not that it will always drop. So pissed.
I honestly think it's a bit retarded how little it drops. 25m not even getting one per kill (and randomly at that, so you won't even be able to assign them to people who didn't get one yet, like you can do with mounts for example) means you could very easily end the extension without ever seeing one, even if you kill the boss every single week.
I'm fairly certain we'll see a slight buff to the droprates soon-ish.
The droprate seems okay to me considering we'll be doing this boss for the next many many months, and they are supposed to be used while levelling up in the next expansion. We killed garrosh every week possible so far and have had 3 of them drop so far.
My raid is currently 0/40. Considering how likely it is to get heirlooms you have no use for or duplicates of ones that do nothing for you additionally, the drop rate is a little extreme. I'm also worried I'm going to win the 1h mace instead of the 2h caster staff, if I ever get one, which will literally do nothing for me or any of my serious alts. The 1h/2h are on both Balance and Resto loot spec (as far as I can tell).
We're probably talking 5% chance or less. It is entirely feasible that many people who kill Garrosh every week (starting with week 1) until the next expansion comes out will never even get a single Heirloom. I can only hope the "lfr-style" safety-net for drops is working in some way for these heirlooms.