I'm not surprised by your experience. There's a reason why Schwinn sold over a million E-F frame bikes.
I wouldn't be surprised if you decided to use this bike as your primary commuter. You really should consider replacing the steel rims. Steel rims, hand brakes and water aren't on speaking terms.
Nashbar has 27" alloy rims on sale for $9.95. These are the same rims I used on my Varsity.
http://www.nashbar.com/profile.cfm?c...eid=&pagename=
New spokes, nipples and a truing stand, and you're all set.