I read through the summary and the deal looks reasonable to me but, and this is the big but, this isn't my area of expertise so I'll be curious to hear from more knowledgeable folks over the next couple of days.
Of course just about every Republican candidate is criticizing the agreement but they're criticizing it as a matter of policy in broad generalities not as a matter of substance. I've yet to hear anything about any specific issues.
Of course if you're convinced Iran should remain permanently economically hobbled then no agreement is a good deal.
The problem is that such a position is very short sighted and very dangerous. We need to get Iran back into the community of nations and we need them to get more involved in the fight against ISIS.
Of course we can expect Netanyahu to go ape shit over this regardless but I doubt he'll do anything beyond whine and cry persecution. See why he gets along so well with Republicans?