Just to follow up:
I tried all the steps that Apple suggested:
1) Restore Network Settings
2) Restore iPhone to factory setting without reloading a back-up
Nothing changed the fact that the wifi connectivity was down to about a tenth of the speed (on average, download speeds down about 1 mbps as opposed to 10+mbps previously)
I finally went to the Apple store, where thanks to my Apple Care plan, Apple swapped my old phone for a new iphone 5. And..surprise, surprise. The new phone work just fine with the most recent iOS and the old backup reloaded straight to the phone. I am now back to enjoying full wifi connectivity with speeds up of 10+mbps). Although the apple customer service was not aware of this particular wifi problem, it appeared as several customers at the store were having issues as a result of the most recent firmware update.
In summary, I continue to like the apple service (which clearly I paid for). However, I also continue to have grimes with the shoddy upgrades and Apple's lack of transparency philosophy.