*SPOILERS BELOW, DON'T LOOK IF YOU DON'T WANT TO KNOW ABOUT THE END AND 2ND HALF OF THE GAME*
Highlight the text to reveal, this contains major spoilers.
I saved all of the little sisters and the ending is basically that you refused the key to Rapture and you took all the girls topside so that they could have normal lives, and it shows that they grew up and got married, went to college, etc; in return you got a "family." I thought this was actually a cool ending to the game having had saved all the little sisters.
I agree that the final boss was extremely easy and the second time I beat the game he barely even hit me (except when he called out the bots and splicers) because it was so easy to dodge. I did think that the ways you kill Both Ryan and Fontaine were unique, rather than just shooting them till they stopped moving. IMO the game didn't drag after you kill Ryan, it dragged a little bit leading up to Ryan but then it picked up again especially when you started to become a Big Daddy. If I had to use one word to desribe the final battle I would say it was tepid
*edited
