It will not "track it" as closely as wanted until the market gets bigger. Since it is not backed directly by dollars from a third party and instead is done in a prediction market style by issuing new steem into the hands of those who convert steemdollars (thus foregoing the interest payments they would receive on holding SBD). It requires higher volume and liquidity to get closer and closer to the peg.
Its actually a great moneymaking opportunity to trade arbitrage steem dollars when it is not as close to the dollar peg. Trust me it is working precisely how bm said it would. What you are looking at is the difficulty of a prediction market to function in the early bootstrapping days. If you look at the bitassets in bitshares they work very similarly and even with lower liquidity still track quite nicely when compared to other (truly 3rd party free) cryptos.