PLOT:It was so fresh and unexpected! I loved the idea of webtoon coming to life(and they executed it perfectly), and Lee Jong-suk(who played Kang Chul)  was the perfect casting choice to play a cartoon character. Every episode had a lot of action, very unusual(in my opinion)to this kind of KDrama.I loved seeing the same scenes we just saw in "real life" ,to then seeing them in the webtoon,it was such a nice touch.  I liked it!
THE CHEMISTRY BETWEEN OUR MAIN COUPLE: Our main couple Oh Yeon-Joo(played by Han Hyo-Joo) who is the daughter of the author of the webtoon "W", and our main hero of the webtoon Kang Chul(played by Lee Jong-suk). The chemistry was there! Was it over the roof? No, but it was still there and that's important!
HOW IT ENDS(*Mild spoilers*): I expected much sadder Ending then we got, that shocked me(don't know really why). For me the ending was satisfying, I really liked the last episode. To be very honest it felt a little rushed, but still good.