I don't know why I keep buying these games... but I do.
Season Two is shorter than Season One by one episode and it recycles many of the old sets. I think this is a bit lame. The individual episodes in Season Two are mainly separate stories, but there is a common thread and some overlap and the last episode brings everything together quite nicely.
The individual episodes in Season Two are more interesting than in Season One and use some clever puzzle mechanisms like portals and time traveling.
The puzzle difficulty is just about right IMO. I got hung up on some parts but not for days on end. I always seemed to move on after sleeping on a problem. Although the puzzles are not as sophisticated as in the Myth series, they are more satisfying in Season Two than in Season One.
I must admit that I don't get the humor in Sam & Max. Or more accurately... I do get the humor, but just think it's a bit pathetic. I must admit that Season Two did make me laugh in places. Timmy Two Teeth was a particular highlight and caused me to bleep my bleeping head off! If the humor was to this standard all the way through, Sam & Max would be a global phenomenon and not just a nice hit. I'll be interested to see what sort of humor they bring to Wallis & Gromit. I was interested to notice that a degree of finger wagging at closet computer game playing nerds crept into Season Two. This is unusual for a computer game, but I suppose it does underline the eccentric humor of Sam & Max.
Overall, I must like Sam & Max on some subconscious level to keep coming back for more. I can't see any reason for me to buy Season Three... but I bet I do.