I'm falling into the "interesting, but not that great" camp as well, after 4-5 missions in, I've just become....bored with the game. There is nothing motivating me to play the game other than just as a brazen action hero at this point, slaughtering foes with ease and then blinking away to a slightly-above-eyesight bookshelf in the room so the guards can fall back into their rote dialog and pathfinding routines.
I understand that I COULD go in stealthily, hide all bodies, and take out the target using whatever scheme I overhear from the mandatory guard conversation which exposes the target's 'big weakness", but what's the incentive besides knowing "I am a slightly quieter bad-ass"? I still get a pat on the back and a completely phoned-in speech from John Slattery when I arrive back at the not-so-secret secret base.
For curiosity's sake, tell me how I was supposed to capture the Mad Doctor in his little greenhouse above the bridge? I waltzed in and shot a sleep arrow into his neck and then carried him down to the boat. End of Mission. There was talk of "strange deliveries going to the doctor at all hours" between two guards so was I supposed to just hide in a UPS package and get up there?