Maybe this is just nitpicking, but WinRAR has an archaic user interface. While there is something to be said for consistency (most WinRAR users can operate it blindly), we started looking around for something that was a little more up to date, and fit more closely in with the windows 7 style.
Searching around, Power Archiver 2010 rose to the top of the heap. It supports all the file types that WinRAR does, as far as we can tell, with similar shell integration and a user interface that has more in common with Office 2007 and later than with Word 97.
The trial being installed, it was time to leave it on the tester for a few days and see how it fared as a replacement for WinRAR, a fairly demanding task, as WinRAR is used more than once a day and has always been reliable.
The long and short of it is, while Power Archiver boasts a much nicer and more thought out user interface, in keeping with newer design ideas from Microsoft, it simply doesn't perform well on our systems. It stalls on load, hiccups frequently, and usually ends up killed rather than closing cleanly.
It's unfortunate, because with some performance and stability tuning, this could be a very nice application. Perhaps this is just growing pains related to recent changes in Windows 7, but as it's in version 11.50 now, one would think it would be quite mature in it's basic functionality. We'll keep an eye out for improvements.
Someone out there will likely point out how stupid it is to replace a perfectly working program with another one just because the new program is pretty. We expect it, and deserve it. Still, we like the shiny stuff, as long as it works as well as what it's replacing.