It's best not to compare it to the first season since the time skip and atmosphere of years past and adulthood change the story and character dynamics quite a bit.

So, as a standalone season;
THE GOOD: I liked that they aimed for a mature atmosphere. The 'youngsters in love' trope gets old really fast, and in season 2, everyone is grown up and their emotions are not all over the place, their reactions to each other are more well portrayed as well. Of the main pairing, GSD in particular, doesn't come across as childish or immature (although he didn't really in S01 either). Also, all the actors maintain great chemistry and their on screen interactions are comfortable (both platonic and non-platonic). The sets are nice, modern and tidy, the story has pleasantly domestic scenes and everyone has a day job, like normal people do. The writers are also quite clearly trying to write something different than the usual, involving a variety of personal and interpersonal problems, some social issues, health problems, an active work environment, complicated parental relationships, etc. And it comes across quite well, mostly, however...

Too much plot, too little time...
THE BAD: Too much going on, so nothing really gets properly developed or given enough time to feel as organic as it could, because in six short episodes, it can't really work. Excess plot ideas are also a problem, they tried a little too hard to keep it 'interesting' and instead succeeded in making it feel cluttered and messy in a many places. For one thing, GSD and ZSY moved on way too quickly from what had previously been then entire future plot at the end of S01. I did manage to surmise that Bing Wei and SZY were in a relationship, but I didn't get the vibe that they were in a 'stable' relationship, because we barely see these two interacting and honestly, SZY acts like a d*** to Bei Wing most of the time. And as for PSY and Yu Zhen Xuan...

Not enough time or research for my tastes, since I'm a stickler for detail and I like psychology based themes and ideas...
THE UGLY: It's a cute pairing in theory, but a pairing between two people with psychiatric problems needs its own fricken show, and getting a happy ending is very, very unlikely. A story like this would be fantastic, but it's not something you slip in as a side story, and especially not an inaccurately portrayed side story. Here we have YZX, who is an autistic character who behaves like 'L' from death note for some unknown reason, and PSY, who is written as having affective disorder and then goes on to behave as, and describe, what is actually an Empathy Disorder. It's a mess. The person who came up with this little plot bunny clearly missed the mark. They should not go down that road if they can't give that story line the time and research it deserves.

That said, PSY is still my favourite character.

I have hope that if they make another season, they do better, but otherwise, if you don't take it too seriously and you're not someone who nitpicks and wants too much more out of a plot, then I'd say watch it and keep going. It's still enjoyable, and it's funny, fluffy and even cheesy, too. The acting is great, as everyone else has said; it really is.
So, it's not a waste of time to watch it, because it is a likable show as long as you don't over-analyze it. And the cast is great.