One risk was that Iranian hardliners would block a deal with the 5+1. Now what are they going to say ? Yes Netanayahu says it's a terrible deal, however it actually is a terrible deal ?
Another risk was that AIPAC fearing congressional Democrats would vote with Republicans to override Obama's inevitable veto of the inevitable deal sabotaging bill. Now that Netanyahu has made the negotiations with Iran a partisan issue, that is much less likely.
I have no idea what will happen, but if things do work out, Benjamin Netanyahu deserves the credit.