Slacker Cats is definitely Disney's attempt at the adult cartoon market (like Family Guy, South Park, The Simpsons, etc...), but it's not even close to the level of these shows, or Adult Swim. But it is a pretty funny show though. LOL.
To be fair, when The Simpons and Family Guy started, they weren't so great, South Park has evolved over time but has always been hilarious, Futurama was funny thanks to Groenings origins experience beforehand. I expect the show to get better over time so long as it's not cancelled :)