One person described it as "totally out of place with the natural area" while another called the photos a "horrific monstrosity."
The plans submitted are looking for permission for two blocks consisting of 97 residential units across five floors.
Three of the apartments are set to be studio while 59 will be one-bedroom and 35 will be two bedroom.
Labour councillor Lettie McCarthy told Dublin Live she'd be "extremely surprised" if Dun Laoghaire-Rathdown entertain the application and that lodging it in the first place was "strange."
She said: "It's not in keeping with the Local Area Plan, back in 2004 all the land around Kilternan was re-zoned from agricultural to residential and then it was thought to have a plan for the area which has kept development at bay as they build the necessary infrastructure.
"That local plan indicates that you can't go higher than three stories so how they think they can double the size and get away with it is just not acceptable.
"I don't think it will go through and I certainly don't think it should.