I spent 4 years in the engineering program at ASU, and I thought the city, school etc. was good. The social scene is pretty cool when you go out (I always had a good time, and never got an STD), and the academics range from great to not so great depending on the program you are in. It is a gigantic school, so dealing with the bureaucracy is painful and impersonal (but that seems to be the same as my experiences with UCLA, and I assume other schools of similar sizes).
If you are coming in as a grad student, don't expect to be hitting the undergrad party scene. Since 2003ish, they locked down the dorms to residents, unless you are escorted in. Over the last couple years, they actually got pretty good at keeping people who don't live there out.
Summers aren't as bad as everyone makes it out to be. April? It still averages 80 degree highs. If that is hot to you, you might want to look into Cornell and Michigan, or even the north pole. That might be better suited for you. It gets uncomfortable when it starts to touch 100 degrees, and that is mid-May. The June-July time-frame will have you jumping from air conditioning to air conditioning. It is reasonable again in mid August (when school starts). The temperatures get so high because the city is essentially an asphalt island, trapping heat all day long. If you drive out of the city on the 202, you can feel the temperature drop 10 degrees over the course of about 5 miles.
On the bright side, it still hits 70 degrees during the day in December.
Hope that helps!