Sam & Max: Season One is made of 6 point'n'click adventure games, connected by the plot of hypnosis.
It's one of the first games to use episodic model of releases. And unlike many others, it used them with success, making TellTale produce more adventure games in similiar fashion. It also seems to be one of few games to be on Steam before it was cool.
Oh, and it doesn't support widescreen. Sorry folks, 2007 year and all.
Episodic model is also used in good and bad way, in a sense that you have common location and few common characters (outside of those that are unique to single episode) that keep reappearing in each episode. Sybil is most amusing, as she changes job every single episode. Such familiarity works nicely. But then, there are some negativity about it too, like, in the last episode you can suddenly pick up object that main hero refused to keep in all previous episodes.
Graphics and music have style to them, even though they are a bit weak. Both of them. Well, or not so weak.
Fine, music is nice, but more of staying in the background. And graphics are fine for cartoonish style. Lacks some good shadows though. But hey, was designed for low-end machines back then.
It's quite usual old-schoolish point'n'click by gameplay and plot, following same mindset of "puzzles are the main point". Which isn't bad thing. Combined with expected humorous approach. Mature one even. You do get few hard puzzles that I am sure you would want to use at least some hints from the almighty Google. But at least you feel clever when solving some of harder ones, at least I did, when figured out Checksum puzzle.
Did I mentioned humour?
Actually, characters interaction and humour is one of the best in when it comes to "old-school by being linear and humor-based", outdoing most of older titles.
It's a pretty nine series. Some may like it, some may not. Others will choke on rainbow bliss. From smiling too much.