HBD works pretty decent when it goes below 1 dollar. The reason for that is that when the debt ratio is below 10% you can always convert it to ~one dollar's worth of hive. Under those conditions traders can buy them below the peg, then do a conversion and sell the hive for a profit. That creates buying preasure for HBD that brings the price back up.
There is no way to create new hbd on demand when the opposite happens. That is what is wrong with the pegging mechanism. It looks like that will finally be included in the code on the next hardfork. In the meantime the hbd stabilizer is basically converting hive to hbd but the demand is too high right now for it to be 100% effective but it's better than nothing.
Here you can see that HBD was tracking the value of one USD for most of last year. The moving averages ranged somewhere between 0.95 and 1.00 most of the time. It is not as good as other coins in my opinion due to the low marketcap and the lack of exchanges where you can arbitrage away the deviations.