I have been using this app for a couple of months since our enterprise exchange server is not activating active-sync (which would allow integration with the iPhone email) and this app allows a much better access than you would get from a simple web page.
New version 2.0 offers easier navigation, better security and faster response time.
I definitely recommend it unless of course you can activate Exchange from your iPhone.
WemailsPlus is a nice workaround !
Pierre Rochette about Webmail++, v2.0