IE7 does a decent job of adding browser features introduced and popularized by Firefox, but the new IE adds nothing innovative to web browsing and is at core a product geared at catching up on web interface standards and emerging technologies.
I recently installed IE7 on my work laptop. This addition was not from any driving inclination but because I need to have a working instance of all major production browsers for work to test and evaluate public website code.
Anyway, it's okay and does a decent job of adding browser features introduced and popularized by Firefox — such as tabbed browsing — but my major reaction is the question: this is it, this is the best the wealthiest software company in the world can come up in the four plus years since IE6 was released?
I think I would have looked more favorably upon the effort if Microsoft just took the time to make IE7 an easy to add and remove stand-alone program, like Firefox. As it is, it's still integrated far too much into the OS, and the required Windows Validation will likely annoy a lot of people who have copied a version of XP onto a second computer and can't install the program.
For those who are interested, additions in IE7 included tabbed browsing, new security, built-in anti-phishing site recognition, RSS support, and better adherence to W3C standards.
Bottom line: To date, I've seen nothing in IE7 that's not already available natively in Firefox or through a Firefox extension, so, unless you're a web developer who needs to test pages in all modern browsers or you just enjoy trying out and using multiple web browsers, I don't know that I would recommend it.