IE7, compared to IE6 gives you better controls over privacy data and managing add-ons. You can set data to be deleted upon closing the browser in 7. The phishing filter was added but in my opinion delays the opening of a page due to taking the time to scan it. It does work though. Adding the tab feature put IE in closer race with Firefox.
I use both and have cases of pages not displaying correctly in both. Not so much one more than the other but it happens in both browsers. Personally, I think Firefox displays faster than IE. IE7 is definitely an improvement over IE6.