I just reached room 899 in the third mission (hotel) to kill the Dexter dude, and while crawling through the vent outside his room I kept going forward and the LEVEL ENDED. I didn't kill the target, I passed by him in the vent, and poof the level ends. No warning whatsoever that I'm about to finish the mission.

If I want to replay it and kill him, I'm gonna have to restart the level because the checkpoints expire when you finish a level, and of course for some god awful reason they just. didn't. implement. a. save. system.

What's weirder is that after the stats screen (including "Target killed = 0") a cutscene plays where Agent 47 jumps out of the vent and gets captured and almost killed by the Dexter dude. Does that mean that because I failed to kill him (by passing his vent and finishing the level), the story goes that way, or that whether passed his vent or not, that cutscene would happen either way?

More and more games are doing it Max Payne 3 style by connecting the gameplay with cutscenes, making it one continuous story with no going back, where I feel like I'm struggling trying to play the fucking thing well yet being interrupted and shuffled around by the story. It's disorienting to have no control over the pacing like this. I can't save, I can't experiment by running around much, there's a mandatory checkpoint and mandatory cutscene everywhere, it's like running through a mine field trying to enjoy the god damned gameplay and failing.

Since trespassing immediately drops my points, and since those who are wearing my outfit can detect me and I have to keep avoiding them (not to mention that there's no maaaaaaaaaap), I end up not really exploring much and just finding single paths to lead me to my target. Am I missing a whole lot by going from A to B to C immediately?

In other words.. For those who understand how this game paces and what it wants me to expect, can you please share your knowledge? Am I not supposed to play it like previous Hitman games?

Another thing I could use tips for is the moronic enemy AI. I'm not sure how to be a ghost around those guys, the lines between trespassing and getting detected or almost-detected or being hunted are kind of blurry.

Edit:

Ok so after all the work I put into getting to the man without being detected, he catches me for story purposes and now I'm running from the cops in a scripted sequence?

You were supposed to enter the vent, there's no way to actually kill the guy.

And there are ways for you to explore effectively. Get a disguise that is permitted to be there but where there aren't many more of that type of person. For instance on the hotel level, there are a lot of guards but not many janitors. If you dress as a janitor you'll be able to explore more freely than if you were dressed as a guard. You just have to find the right disguise for the occasion.

@OfficeGamer: That's exactly how that scene is supposed to play out. So, don't stress too much! If they had wanted you to really kill him to complete the mission, they would have failed you at the end. It was just a scripted end of the level.