Iansluggy

I have applied for PhD programs in pure mathematics and I have received an offer from a school that is ranked very highly for my subfield, but is a mediocre school overall (~60th US News). Based on the email I have received and the financial offer, it seems like they really want me, which is exciting, but I am wondering if I should attend a university with a more well-rounded math department. How will going to a school with a very strong research group in my subfield, but mediocre reputation affect my graduate experience, as well as my postgraduate prospects?