I work in the IT Security industry as a consultant and from my own experience it's a lot safer then previous versions aslong as you secure it up properly.
It will probably suffer the same buffer overflows over time that other version's of IE have, this is due to it being so popular not due to being rubbish.
If you also notice hackers are turning their eyes towards Firefox more and more as it gains popularity.
The trend in hacking these days is to make money, so they want to run a browser based exploit and install a back trojan when can then be used to launch DDOS attacks or exploit money directly from you by encrypting files etc. to this point they will go after the browser with the biggest audience for the greatest chance of success.
One thing I do is automatically block all 3rd party cookies, this is mainly to stop then horrible marketing agencies filling your machine with rubbish and then allow 1st party cookies, also run at a high - medium level and block popups.
I tied blocking scripting completely but this stops a lot of websites to stop working.
Make sure you have the phising filter turned on, if you think a link looks dodgy don't click on it as simple as that. If you want to kow if a sites safe, download this tool from
www.siteadvisor.com, it is awesome and doesn't impact your browser and best of all FREE
Active X is also a big security risk but it's down to you whether you want to turn it off.
On top of all that make sure you have to date AV and Anti spyware software.
I use both IE and Firefox and have no allegience to either, I also use Linux and Windows.