One of my favorite dramas to watch (I've seen it at least 3-4 times now), even though it might not be the BEST drama ever made (Nirvana in Fire, rightly earns a place as best drama ever),

STORY:
The story honestly is fairly simple. There's no crazy twists and turns. Not a ton of plotting and backstabbing, etc. It really just is a very simple and beautiful telling of two people falling in love and growing together.
 The super fun twists that I think most people enjoyed were the great transitions between real life and the gaming world. Definitely something refreshingly new that gave you the best of a modern drama with sprinklings of wu xia.
I really appreciated that even though there were other people who had feelings for the main leads, you never really got the feeling that something could come in the way of the two leads. They just had a pure relationship that was based on similar interests and general good chemistry - not because they were forced together by circumstances or one of them was love lost and then they found each other.
They both honestly enjoyed each other's company and felt very natural with one another. It's really not something you get all the time.
Very well paced out and never felt rushed or lagging at any part.

ACTING:
Yang Yang - Xiao Nai - Wow. What a great performance. Yes, his name was already ringing in circles after Dream of Red Mansions, Lost Tomb, etc. But I would definitely say this drama catapulted him into stardom. Xiao Kai had the tropes of a standard male lead - well off, smart, super popular, beautiful, somewhat introverted - but Yang Yang definitely did a fabulous job making Xiao Nai break past the standard topes and bring about those cute swooning moments that girls (who were really the target audience) love to see in dramas. Every interaction was playful but serious. The kiss scenes and other romance scenes were really mostly due to him.
Zheng Shuang - Bei Wei Wei - While she did a decent job in her role - very smart and hardworking, but still shy and cutesy at times - she was definitely overshadowed by Yang Yang in this drama. Most dramas I watch, I almost always feel like the female lead overshadows the male leads (especially when the story is more revolved around the girl), but Yang Yang was definitely the one driving this performance. The romance scenes, Zheng Shuang was like a wooden board at times (which many other people have critiqued). Being new to a relationship is understandable, but even further into their relationship, it was Yang Yang doing 75% of the work. She's been a very popular actress lately, but I honestly don't really think she's all that great. She does cutesy very well, but I don't feel like she's broken past that yet.
Xiao Nai's Friends - Great chemistry between them all. I think they all did a great job with their respective characters. Hou Zi was the flattest character of the three, for me, but wasn't bad by any standard. Yu Ban Shan and Hao Mei did great jobs showing off their characters' personalities and the loyalty they had to Xiao Nai and each other.
Wei Wei's Friends - Only Mao Xiao Tong (Zhao Er Xi) really had enough screen time to be a developed character, so she gets props for portraying Er Xi's happy go lucky character so well. The other two were good in terms of being the friends, but definitely didn't get a chance to show off much of their acting skills.

REWATCH VALUE:
I've already rewatched it a bunch of times, so obviously worth a rewatch. Even though you know the whole story, it's still cute and romantic enough to be a good rebound after a super lengthy period drama or a very serious and dramatic show. It doesn't really get boring for me because even though it's not something you have to pay a ton of attention to to understand, it's not really a brainless show that you just play in the background either.