Having been using these recently I wanted to comment on them. There's still some guys here that use the older cartridge razors, and this is one of the best multi blades I've ever used.
To start off, these aren't the Twin II Plus blades with the lubricating strip, these are the non-pivoting, non-lubricating blades made by Personna for Trac II type razors. I'm currently using them in a Bump Fighter razor. I scored both at Wal-Mart for around three dollars and some change each.
The blades are sharper than what I expected from Personna. I've used their version of Sensor Excel cartridges before and was disappointed. The blades were downright dull compared to Gillette's Sensor blade, and I only got two or three shaves before they went into the trash.
These seem to be much sharper, and I get at least five good shaves out of them before they begin to dull, on par with the Mach III or Quattro blades that sell for five times the price. The shave itself is very clean and close, but not "strip your epidermis" close. The lack of the goo strip means that these cartridges rinse clean easily- a problem I've had with Trac II blades with a lube strip. I for one have an aversion to pivoting heads, so the Trac II fixed head design calls to me, and these blades do the job well. One pass is all I need out of the Twin II's.
At 3.29 for a ten pack, it's costing me about six cents a shave for a DFS. That's a good deal anyway you slice it. Paired with a 3.60 Bump Fighter (Trac II) razor, I'm in budget shaving heaven.