Seems like an attempt to make a spinoff of Scooby Doo while channelling the adult tone, wit, and sarcasm of an old favorite - Daria... and failed miserably.
It doesn't capture any of the fun and nostalgia of Scooby, while the more adult humor simply fails to be funny. Shock and snark are no substitute for intelligent and witty writing.
If the show gets a second season, HBO needs to fire the current writers and find replacements with an actual sense of humor and higher than room temperature IQs. That is assuming the show doesn't make a major turn around in the remaining episodes, but given the awkward and ham fisted approach so far, I really doubt it.
It's not a bad show concept, just a horribly botched execution.