Every season has been solid. They definitely haven't mailed in it after all these years.
The characters certainly evolve over time. Frank, Dennis and Dee become more depraved people as the show goes on. It's also nice seeing the recurring characters like the waitress, the McPoyle's, Rickety Cricket, Maureen Ponderosa, Charlie's uncle, the moms, Mac's dad, the lawyer guy they always have problems with, etc.
The more recent seasons have fewer episodes - ten total. So the product doesn't get diluted down with a ton of episodes each season and they are able to keep content fresh IMO.
It is interesting how the show went from being at the pub all the time to barely seeing the pub at all now. We didn't even see the pub last episode yet they still pulled off a fantastic episode.
Next week looks good:
After finding out she's a male stripper's "rock bottom," Dee goes on a mission to prove she's the best thing that ever happened to him. Dennis takes over for the stripper with the help of his bag boy, Charlie. Meanwhile, Mac and Frank get sucked into a VR war game that causes Mac to develop his own case of PTSD.