I still don't think the drama deserved the hate it received right from the beginning. How people could go and judge it after 4 aired episodes is beyond me. So I'll try to give this constructive criticism, because I don't say that this drama is a masterpiece when it isn't.

After the first 4 episodes I had a blank mind, couldn't say if I liked or disliked the drama. I didn't feel bored, nor excited.
It's the same after I completed it, just that my head is now full of thoughts about all the questions that were left unanswered. I won't go into detail but if you like your drama end to tie all loose ends, look elsewhere because the writer left us with lots of empty room for interpretation.

What's positive about the story is the setting and the idea itself. I found it interesting and still think it could make a good drama. Sadly, as the drama kept going it only got more confusing. There were some moments when I wasn't sure if I missed something or the scriptwriter herself got more and more confused with all this traveling between worlds.
It might have been better to keep it more simple but that's not how it is. And yes I have to admit there are some filler scenes that we could do without and plot holes throughout the drama. But just as much plot holes there are product placements which personally I find just as distracting and annoying.

Bottles with coffee, chicken, food delivery service, beauty products, bakeries, car brands and more. The most annoying for me was the coffee and beauty stuff. More than once it looked like I had accidentally turned the teleshopping channel on. No joke!
We even get praising lines with this products telling us how good it tastes or an explanation how to use the beauty product. This might be allowed but it's definitely not what I want to see in a drama. Sponsoring is okay and important, I get it, but please don't shove those products in our faces like that and mess up the flow and logic of the story with them. There were nice and dynamic scenes that lost their meaning when another product popped up and stole the attention. There are way more subtle ways to do this...

The whole cast did a great job and the acting was really good. If anything I would blame the scriptwriter that made the female lead cry so often and not the actress for having to follow the script. It was my first drama with Kim Go Eun and Lee Min Ho and I liked them both a lot. Woo Do Hwan was the only one I knew from the cast/who was already among my favorites before this drama and he once again showed how good he can portray different personality types. I enjoyed every scene with him the most. I would wish for more scenes with him and Kim Yong Ji who also left a good impression. ^^ I liked the acting of Jung Eun Chae and Lee Jung Jin. Sadly their characters kept staying pretty much in the dark.

The OST is good, probably not going to be a favorite of mine but it's fitting the scenes of the drama and also nice to listen to on it's own.

As for the rewatch value. Chances I'm gonna rewatch this drama are pretty slim. Maybe a few scenes, mostly from the first couple of episodes when the traveling still caused funny scenes and didn't turn into a who's who.

I recommend everyone to go and see for themselves if this drama is to their liking or not. As I said, it received a lot of hate and I think not all of it was fair and appropriate so go and decide for yourself. Maybe this is your next favorite?
For me it was decent despite flaws in the writing and how the story progressed. I don't regret watching it, just think they could've done way better.