What bookshelf speakers do you have now?
I have the Polk center. It looks nice, is compact, and seems to be very well built. But it sounds pretty 'warm' to me, with a noticeable drop in output around in the upper mids to low treble, compared to other center speakers I have.
If that's what you like, it's a great deal.
If that's not what you like, look elsewhere.
I have no experience with the Harman.