I personally found Alice to be a fun and exciting show. The first few episodes were especially good. It's towards the end that things became pretty complicated, and while I appreciated some of it, I also wanted more. For example, I wish that Jin Gyeom's past with his detective father-figure wasn't erased.
I also never read his relationship with his mother as romantic like some of the other viewers have, but it was sometimes too close for comfort. Jin Gyeom said he doesn't feel any romantic interest for anyone, which did provide some relief in that aspect.
I did enjoy the characters and the acting. I thought Joo Won did a really good job of balancing a lack of emotion with the character's more emotional moments. I also enjoyed Tae Yi as a smart and pretty capable character. I thought the show nicely balanced humor, emotion, and suspense.

This show certainly isn't flawless, but I don't really nitpick flaws and rather judge on enjoyment There are some things I would change about the ending, but I'd still recommend Alice as an exciting and enjoyable show.