Well as the OP has already made up his mind about buying the game i cant complain but for those who said the game is not good,well,that is simply not true people. Either you did not play the game at all,or did not play it the way it was supposed to be played!
Someone said that no matter what you do and who you kill,the ending isnt effected much,well if you had actually payed attention at ALL,YES IT DOES! Did you even stop and try to listen to the dialogue once or twice? Every thing you do is literally portrayed at the end. I can give about 3 such examples from the top of my head.
And the guy who finished it in 11 hours,there are a few things that you might have done to be able to pull that off.
1: You played it on the easiest settings and did not try to benefit from the original play style of the game at all.
2: You went COD on its a$$ and again didnt play it like was supposed to be played.
3: You did not explore at all which in turn did not give you any awesometastic powers and abilities to use instead you just went with the gun and run tactic.
And if you did any of the above,then i cant blame you if you did not like it.
Yes the game can be played by either being like a crazy murderer assassin and killing everything moving which i did or going with the stealthy approach. What used to do was,stealthy move pass all the enemies,complete my objective and then come BACK to kill everyone
For those who are starting now,i will recomended you the following abilities and powers depending on your play style:
For stealth,Powers: Agility (its level 2 is amazing,its the only power i regretted i didnt get sooner,combined with the foot equipment or something upgrade which masks your footsteps you can sprint past enemies or kill them without crawling up on them slowly and slowly and then getting found out),Blink is a must and finally possession. Get these first and foremost.
For Weapons i suggest you upgrade the bow to its final form which is like an automatic arrow launcher which can kill an enemy with one headshot no matter how far you are IF done right.
For the.."non-Stealthy" approach which is fun on its own,Get Blood thirsty (extremely usefull in the latter fights and fun to watch

) SHadow kill and Windblast is a must!
Weapon wise,upgrade the pistol to its final form which will cost quite a lot and not possible early in the game like the bow,but when you are done,its freaking amazing,i didnt wana be stealthy at ALL after upgrading it.
It took me about 19 hours on normal to finish the game and i only missed just 1 bone charm,explored and found almost everything and missed only those side missions which were optional like either choose this one or that one.
A note for newcomers,no matter how difficult it looks,there is always another way then going through the front,look carefully.