I actually prefer this to the previous ultimate assassin games. The guards continuing to search and being able to take the exit when the guards are searching are both great additions.
Good game but level 17 is terrible. All the first 16 levels require you to be strategic but level 17 is just about being swift. It really sucks not get to play the last three levels of a strategy game because you're not fast enough.
It's really annoying how weak unidentified organisms raining from the sky keep you from having killed every enemy and can therefore course your timer to run out.