That is the noisiest side of the building. You are better off purchasing one on the west side. If that is all that is left and you love the unit, then go for it. You can do some real negotiating over price, up-grades and HOA dues credits. Arterra is not my favorite building down on Berry and within Mission Bay so perhaps I am not the best person to answer this question. I think others have better laid out floor plans and/or square footage. I am happy to talk about the others in Mission Bay and South Beach. Too many to list here.
My other suggestion is to take an independent realtor with you to help you negotiate. This may not happen but I think most developers would make an exception (since you did not take a realtor with you on your frist visit most do not want to pay that realtor a commission.)