My wife and I recently finished season 4 the other day. Wasn’t as good as the previous seasons, I will say. But still a decent season.
Chuck hasn’t changed much since season 3. The Intersect 2.0 still makes him a pretty big super spy.
We find out that his mom is still alive and she actually worked for the CIA, just like his dad. She was a pretty likeable character, once we knew everything about her.
I think the glue that kept season 4 together was the villainous character Alexei Volkoff. Timothy Dalton did a great job portraying the character with multiple personalities to deal with.
His daughter Vivian was a letdown. She goes from pure and innocent to evil and corrupted in a pretty short manner of time.
And at the very end of the season, we finally see Chuck get married to Sarah. It seemed rather rushed, I always imagined it differently.