The key provisions of the deal are already public. Iran won't get any closer to an atom bomb for 10 years, frequent controls will take place, and if there's any reason to believe Iran isn't playing by the rules, sanctions can be reinstated with the snap of a finger. There is literally no downside for the US, unless you think Iran is inherently evil and should be crippled economically regardless of the nuclear issue.
Antonio, you don't understand. Republicans just know in their gut that this deal is bad because it is signed by Obama.
Haven't you heard the concept of truthiness?