As someone who watched 8 out of 10 of Hong Sisters dramas [I have NOT watched Big and Hong Gil Dong],
it's undeniable that Warm and Cozy have the same basic outlines as in their previous dramas.
It's actually the biggest negative for me in this drama.

I can find at least one similarity to each one of their dramas. Here some examples:

  • Unnecessary time skip (Master's Sun, My Girl)
  • Spiteful 2nd female lead (My Girlfriend Is a Nine-Tailed Fox, Couple or Trouble, Choon Hyang)
  • Nice 2nd male lead (Greatest Love, Master's Sun, You're Beautiful)
  • Pull and Push / bickering (Couple or Trouble, Choon Hyang, Greatest Love)
  • Male lead is obsessed with his first love (Choon Hyang, My Girl)
  • Couple living together (Choon Hyang, My Girl, Couple or Trouble)
  • Noble idiocy (My Girlfriend Is a Nine-Tailed Fox, Choon Hyang, My Girl, Greatest Love)
Can you think of more similarities?
I'd say Master's Sun also had the 'First Love Obsession' (if I remember correctly!)
I agree actually. And it's not even that it shared those elements that I felt was a negative, but that it was so generic and unimaginative compared to previous titles.

I agree with Samsoons too regarding the 1st love obsession, though I guess it wasn't because he still loved her, but the unresolved issues. Just my take though.

I've seen Hong Gil Dong and instead of a spiteful 2nd female lead, it was the 2nd male lead :P It also had some noble idiocy, but for the most part (from what I remember at least) it's completely different. I still haven't seen Big since I've been a bit hesitant after hearing such negative reviews of it. But it's one that I hope to watch soon so I can say I've seen all of the Hong Sisters titles. I've seen most of them and so far Warm and Cozy is my least favorite which is surprising considering the actors involved and the set up.
Their dramas are way too formulaic and predictable for me. I see blatant similarities and patterns in every single one. I tend to avoid them now.
@Danni - I knew Master's Sun had some First Love Obsession related plot but I couldn't remember exactly what it was ^^ I recall now, didn't he have a memory loss concerning what exactly happened with her? Anyways, I agree with you. I haven't seen them all, but I think Warm and Cozy was very similar to Fantasy Couple on the side characters, setting and occasionally, the music too. 

Oh and Spiteful 2nd female lead - My Girl had one too: Park Shi Yeon's character.
I'm completely with @dbani on this one. I've written off the Hongs for good. I find their stuff to be very lowbrow and not worth the time investment. I do plan to have a look see at Big just out of morbid curiosity. I know I'm going to regret wasting my time, but this is how Asian dramas make masochists out of people.
Those are my drama go-to when I'm in a drama slump, cuz they kind of 'easy' and refreshing plus the lines are beautiful and carefully written, it gives real good feelings. But I like how most of Hong sisters' dramas have really good and captivating OSTs

Haven't watched Master's Sun yet, though it's on my list to watch.

I agree though I think they improved a bit with Korean Odyssey(I guess the thread is older so no wonder it's not mentioned). It had more oomph than the others. While there is some Pull and Push, it's fine. Who knows, maybe they saw your posts and changed their ways :P. Odyssey is right after Warm and Cozy.

Watching Warm and Cozy now. Pull and Push is strong on this one. It has taken far longer than it should.

From the future here too cheers for the Hong sisters they went out of their comfort zone with Hotel Del Luna. Still have some first love type of stuff going on.