Overall: enjoyed this a lot, will probably watch again

Liked:
The main romance. It felt natural and believable and funny and sweet. Both actors were adorable and excellent. So Ji Sub has this 'vulnerable' face he does that just... melted me. Shin Min Ah's dimples and 'determined' face were very appealing too. They didn't do the 'frozen kiss' thing, and had fairly realistic, nice love scenes; and they didn't do too much of the self-sacrificing thing, aside from his hospital trip, which was kind of weird but made at least some dramatic sense given that he'd always dealt with pain alone - and that wasn't dragged out for too long.
The buds. Loved the boys. Her best friend and the 'growing sprout' were nicely done too, and his relationship with his secretary/minder/whatever was quite touching.
The families - her mother was very cute, his father and grandma were believable (I didn't care much about the rest)
Her job. She had a good reason for becoming a lawyer and had worked hard and struggled for it, and was supporting vulnerable women.
Her 'health journey' - I found it believable and fairly inspirational (I ate a few cleaner lunches while watching it) and liked that it focused (mostly) on improving her health.
The make-up for both leads - she looked genuinely chubby and he looked genuinely as though he had been ill a lot.

Disliked:
Way too many flashbacks. So much use of the skip button. Worst thing about it.
The secondary romances. Ex-bf and ex-friend were really annoying and boring, and the girl who kept hitting on RFC Champ dude just felt like a stalker.
The music was overdone in a lot of scenes, but most especially with the flashbacks.
I have a personal beef with 'just eat it!' for foods that might make a person sick.