I enjoyed it. It was longish, not too complicated, and the visuals are great - the "western" comic book style is a nice change from the usual VN-anime/manga-look.
I have no clue which ending I got, but it felt like a satisfying conclusion.
Some of the "game overs" are a tad random, but since you can always "mousewheel-up" to the last choice, it's tolerable. I really enjoyed the hangman-style-minigame - the "remember this set of numbers" minigame I could have done without, though.
The whole story kinda reminded me of the X-Files. I guess the chemistry between the two main characters could be improved in potential sequels in that regard - since this is the first part, it's okay, because the two of them just met, but I'd enjoy some more banter and / or sexual tension.