Things I do every day are generally archiving files as backups, for which I mostly use command-line archivers in batch files run from a scheduler. What special features PowerArchiver do you need that aren't in other programs?
Keep in mind that I haven't kept up on the recent advances of other archivers, but when I made my purchase PowerArchiver was far and away the fastest of those I tested. The Explorer-integration is unmatched with everything you can possibly need in the context menu (you can add & remove to your tastes)and actually has aesthetically pleasing icon types for all your archives along with a very nice UI. That's a niggle, I know, but archiving programs are usually infamous for having very homely icons & a UI only a mother could love.
There's also functionality to email, burn, or FTP an archive without having to go through a ton of mouse-clicks. There's a backup scripting engine that will make short work of any backup jobs you might want to accomplish without having to resort to using the CLI, but there's a command-line component as well if you are interested.
What I believe to be a unique feature is a queue system that will, if you'd like, queue up numerous archive operations and work them in order so your hard drive isn't thrashing while you try to unarchive a dozen or so zip files all at once. Oh, lest I forget, there's also a preview panel that accepts Total Commander WCX plugins so it's extensible to recognizing more file types.
Of no use to me, but I'm sure it's important to others is Outlook integration and the international version has been translated into 20+ languages...not just the program, but the help file itself.
Something that they have been really excited about lately is they recently implemented a new auto-update system that will download the minimum amount of data needed to upgrade your install to the latest version. No more having to download the full installer unless you want to.
As of today's e-mail, still listed as "coming soon."
Today's the day. $13.98 for the English version & slightly higher for the International version. Lifetime updates.