I was going to write up an article about the significant issues browsing in IE on Windows Mobile 5. Before I could write it though, Ars Technica beat me to it. The article is completely correct; Pocket Internet Explorer is pretty much worthless. I've only found one good feature: when you download a program's setup CAB file, it offers to open it to install automatically.
If you do any website development, and have ever experienced a compatibility issue with Internet Explorer, then this article will be interesting to you. Mozilla is working on getting both the canvas element and Tamarin supported natively in Internet Explorer through ActiveX controls. While the Ars Technica article doubts that many will install such plugins, a few big backers, such as Adobe or Google could make a major change in the web browser landscape. Imagine if the Google Toolbar came bundled with additional controls to fix IE's broken CSS, add support for tags and selectors Microsoft decided not to implement, and speed up Google Maps to boot (by avoiding the ExCanvas library). Exciting work!