As it was with the version 6, compared to 5, the 6.1 is better optimized, which results in overall higher performance and faster loading of menus, with the hardware being unchanged. An improvement that will concern the Internet fans is the new Zoom feature in the Internet Explorer. As the browser of other phones, it zooms out and fits the whole page on the screen, to select the area you view, avoiding the scrolling. However, everything else about the browser is the same, which is definitely not the best on the market. Probably inspired by iPhone, the developers now offer “SMS Chat View Mode”. This makes it easier to have a conversation using text messages, since you can see the whole history, as in an instant messenger. The mobile variant of Office is now updated to open Office 2007 files (.docx, .xlsx) and features one new application: One Note, which is used for voice recording, drawing, etc. Other changes are just minor.
Source: PocketPT via MSMobiles