If it's the one I'm looking at right now in eBay Motors with the thumbstud (the only Tomcat II on eBay at the moment), the knife is a winner. Not cheap, but definitely a winner.
SOG makes quality products. They're a medium-to high end manufacturer and their products reflect that. So quality control isn't a concern.
The center-spine lockback has been around since at least the 1980s. It works well and is secure enough for normal usage. There's so much hype about the latest "miracle lock" that it's easy to forget that a lockback still works very well. A whole bunch of Spydercos still use the mechanism with complete reliability, so does Buck, so does Gerber.
AUS 6 is an acceptable stainless steel. It isn't the latest "miracle steel", but it holds its edge reasonably well and has decent rust resistance. Let's not forget this is nearly a 20 year old knife! Some of the latest steels out today weren't being used in production knives back then.
If we're both looking at the same auction, I would be more concerned about the seller, more than SOG. They can't even get their description straight.
Handle: Kraton
Then in the description they claim, "The Tomcat II comes in a beautiful Cocobolo wood handle."
So which is it?
Probably Kraton and the seller just cut and pasted the ad copy. But that's already a sign of a sloppy eBay seller. They don't care if the auction description is accurate or not. Right from the start, you're going to have to contact them to clarify that.
Checking their feedback they do a lot of business but they seem to have consistent problems with slow or no shipment of goods and periodic "backorders".
Considering the price, it's your call.