I'm not going to spend much time commenting on the Iran nuclear deal, since every talking head and blogger is already doing so. The deal has outraged Israel (or at least its Prime Minister, though there is no shortage of Israelis willing to give it a chance, including some senior security people) and Saudi Arabia (where alternative opinions tend not to get expressed), as well as both countries' allies in the US Congress and media. Israel, the Saudis, and the US Congress constitute a formidable opposition with the ability to screw up implementation, but the agreement of the P5+1 also constitutes a powerful lobby. There are also, obviously, competing factions inside Iran.
My own response is cautious optimism. During the Reagan Administration, I was not fond of quoting Ronald Reagan, but in retrospect, "Trust, but verify" seems a good motto for any disarmament negotiation. Iran has sought to conceal aspects of its program in the past, but the new agreement calls for intrusive inspections which, if implemented, should guarantee compliance. And this is an interim agreement, initially for six months but with a goal of a final agreement within a year.
A lot can go wrong: internal opposition in either the US or Iran could block the deal; a longer-term agreement could remain elusive; an Israeli preemptive strike could derail the deal and lead to regional war.
The deal faces enormous, perhaps insurmountable obstacles. But I personally feel that it's better than any available alternatives. Let's give it a chance.