The problem is that current rules for shorting are just too complicated and/or not properly lined out somewhere + barely working wallet + 30 day expiration thingy. I have high hopes for 2.0 in this regard.
Personally I would like to short some bitEUR but due to said reasons I just find it too risky currently.
I don't know for the windows wallet, but the Mac wallet works perfectly, and I have been successfully shorting without problems for a year now. The 30 day expiration is not a problem at all since nobody shorts at price feed anyway. Some behaviors are weird (when you short over price feed you don't actually short the amount of BitAssets that was indicated, but the amount that the indicated collateral can afford)
At the protocol level, the shorting mechanism works very well. The only risk is a new crash in BTS price.