I'm not sure if all would agree with this but I am finding that at the lower PH levels the weighting of the hall seems to be too high in the 50% calculation. I understand that the weighting is done by the HP of the building and that seems pretty logical to do (in fact in "other" games I had always thought it might make more sense to do it that way). However, I'm noticing that in certain circumstances 12 out of 18 buildings or so can be destroyed without hitting the 50% mark. I think this ties two stars too heavily to the destruction of the pirate hall. this issue (or perceived issue rather) probably dissipates the higher you go in levels since the mix of HP becomes more distributed, but at lower PH levels it definitely seems out of balance.
There's no question this is an issue at very low levels. Essentially you have to destroy the PH to get a win, however low level troops just pound away at the PH until defenses kill them. Perhaps a slight tweak?
Even more of a problem for me is if I am sniping the town hall away from enemy fire I have to use a majority of my troops or they do not destroy it in the allotted time.