For all of its buttons, it appears to be a model toward the bottom of the line.  No china guard under the upper wash arm and nothing adjustable about the top rack.

That doesn't mean it won't do as good a job as its more expensive KitchenAid contemporaries though, but be advised that even with "Quiet Scrub" it will still make more noise than a modern day machine.  Cycles are short, so for best results you'll probably need to use industrial/institutional detergent that contains phosphates,  something like Cascade Fryer Boil-Out, or use a phosphate additive with detergent from the supermarket.  Today's phosphate-free detergents need much longer wash cycles to clean effectively. 

This machine is either a 23 or 24 series, which makes it around mid-'90s vintage.  The common complaint from some people is that these machines (series 21 and later) offer only a single final rinse. 

They shouldn't be asking more than $100 for it.  

I wouldn't say it's a "so/so" machine.  It will wash as well as more expensive models made by KA, and regardless of make, all vintage dishwashers benefit from a phosphate assist. 

My apologies if I made it sound like this machine wasn't worth pursuing.  This is an above average machine from its period across all makes (it has the Whirlpool-improved power module) so if it's priced right, it should serve you well.  Sometimes the machines with fewer bells and whistles can be the best performers.

If another KA of similar vintage shows up that you find more attractive, you can always keep this one for parts.