Gamers and die hard fans are sometimes hard to please, sometimes unfair to producers and sometimes they are right.
Concerning ME3 all of the above is true.. the ending is bold and everybody should judge for him/herself. I don't put much stock in fan reaction to anything because i tend to make up my own mind and found that often enough i have a different view than the majority.
I enjoyed the ending for what it was and didn't analyze it to death.. it was something unexpected and time (and maybe future DLCs) will tell if it holds up.
Enjoy the game, it is truly one of the best gaming experiences i ever had and no ending could ruin that.