I liked Big overall, but there were some things that I noticed that I think could have been improved. The first 10 out of 16 episodes had some really comedic moments that helped balance some of the more serious topics, but then after episode 10, things became more serious and the drama as a whole lost its comedic flare that balanced how heavy the plot became, making it more of a melodrama than a comedy. Also, the drama was pretty fast paced up until episode 10 and then after that, everything was dragged out and the ending was just too slow in comparison to the rest of the pacing of the drama. I also feel like the ending scene where the MC's meet again was supposed to be symbolic, but ultimately failed in being poetic because by using Gong Yoo as the actor, it made it confusing for viewers to understand definitively what happened. I kinda feel like the writers kept Gong Yoo as the main visual for Gyeung Jun instead of using the little brother's actor was to try to distract viewers from how young the younger brother's actor looked that way viewers wouldn't notice the "nouna" relationship as much since Gong Yoo looks more mature and manly. Which leads to my question, why didn't they pick a different actor for the younger brother that looked a bit more mature instead of so pubescent?

I did enjoy the drama for what it was, but after episode 14, I kinda just wanted to skip to the ending and just see how it ended because I was getting bored. The writers essentially repeated the same conceptual conflicts between the two MC's to draw out the ending and that just made me bored. I also think that having Gil Da Ran deny her feelings once for Gyeung Jun was enough - there was no reason to have her confess her feelings and then when things got tough for her to go back on them, break his heart, and then boom, they love each other again. It was just too much of the same shit and I think there was a better way to go about getting to their happily ever after. Also, Gil Da Ran was way too gullible about Gyeung Jun losing his memories prior to the ending and that just got on my nerves.

Overall, I think the story was creative and the "plot twist" was believable (parents really do that to/for their children, as despicable as it is). I just think the plot and flow of the drama would have been better if they had maintained the comedic aspects throughout the entire 16 episodes and lightened up on the melodrama in the last 6 episodes.

What I did absolutely love was Gil Da Ran's brother. He was so sweet and caring toward his sister and exceptionally suave in his pursuit of Jang Mary. He never failed to make me giggle and wish that he were my little brother.
Something else I really appreciated was how Gil Da Ran didn't just all of a sudden develop feelings for Gyeung Jun and that their relationship developed over time. The writers also did a nice job showing how torn Gil Da Ran was in being unfaithful to her fiance instead of just jumping ship the second she began to waiver.
I also appreciated that Gyeung Jun tried his best to respect Gil Da Ran and Dr. Seo's relationship by not being overly aggressive in his pursuit for Gil Da Ran, so initially their relationship kinda fell into place. I do kinda wish that there were a couple more romance scenes with them though.

I probably wouldn't recommend this drama to anyone unless they were avid Gong Yoo fans, which my mother is, so she said even though she didn't like the ending, it was worth watching just to see Gong Yoo's hunkiness ;D.
Gong Yoo is an exceptional actor and did well portraying both Dr. Seo and Gyeung Jun's characters. He did a great job portraying an adolescent as well as being flirtatious and charming.
I'm not too much of a fan of Lee Min Jung, but she didn't do a bad job in this drama. I think she fulfilled her role decently.
It was weird to see Suzy playing the "bad" character even though she wasn't actually bad, she was just a character that wanted what she wanted and got what she wanted.

Anyways, this review on Big makes it seem like I didn't like it, but honestly, it was a good drama, I just think things could have been done a bit differently toward the end to make it better received and make more logical sense.