The plasmid itself is not really that interesting without the topoisomerase bound to it, is it?

I agree with Magnus, topoisomerase is the key to design this vector. I Get what Paritosh want to say, You can grow TOPO TA and get the same result if it has to do only with RE sites. 

That's true, you can make a regular vector for blunt end cloning as described and clone in your PCR fragment with a ligase.

I have no idea though on the efficiency of ligase vs. TOPO blunt end cloning.