We changed 2 out of our 3 phones from Sprint to Verizon yesterday. (etf be damned)
I'm in a populated area (Nassau County, Long Island, NY) and it's not even comparable on 3G.
In fact I have a droid incredible that I activated while I wait for my i5, the dinc is next to my Sprint nexus s and it's some kind of a joke.
I receive alerts (email, google voice, Facebook) in about .5 of a second between my desktop (verizon fios), droid incredible (verizon 3g), and iPad (verizon lte). The Nexus S will mosey along and just chime away whenever, it's hard to calculate but it's probably never been within 10 seconds, while at most I've noticed notifications minutes after.
The VZW droid incredible is OLD and absolutely destroys the Sprint Nexus S in terms of sending text messages, emails, getting driving directions, etc.
I've been frequenting Sprint's own forum and it's just full of distressed customers:
http://community.sprint.com/baw/community/buzzaboutwireless/network-and-coverage?view=discussions