Which statement in chapter 12 of The Giver shows the Giver's dislike of sameness?

Jonas learns that the community once had colors, and The Giver explains to him that they gave up too much for Sameness.

The Giver teaches Jonas about the Capacity to See Beyond, which means in his case that he can see the color red.  Color was one of the things the community gave up in the switch to Sameness.

The Giver chuckled, suddenly. "We've never completely mastered Sameness. I suppose the genetic scientists are still hard at work trying to work the kinks out. Hair like Fiona's must drive them crazy." (Ch. 12)

The community does not allow anyone to be different.  People have the same skin tone, and the same hair color.  They even have the same eye color. Everyone in the community has the same dark eyes, but Jonas’s are light-colored.  The Giver and baby Gabe also have these light eyes.

The Giver shows Jonas the memory of the sled again, which is the color red.  Jonas says that the color red he saw was beautiful, and The Giver agrees.  He tells Jonas that getting rid of colors was part of the choice to go to Sameness, which meant gaining control, but also giving up a lot.

"Our people made that choice, the choice to go to Sameness. Before my time, before the previous time, back and back and back. We relinquished color when we relinquished sunshine and did away with differences." He thought for a moment. "We gained control of many things. But we had to let go of others." (Ch. 12)

It is clear that The Giver does not completely agree with the choice the community has made.  Sameness meant everyone feeling comfortable all of the time, but it also meant giving away beautiful things and pleasant things along with the terrible and unpleasant ones.  He explains to Jonas that it took him years to come to the same conclusion Jonas did, that Sameness was not all it was cracked up to be.

Jonas is told that he will acquire wisdom with the memories.  The Giver explains to him that part of that wisdom is in understanding the community’s faults.  Until now, he has done nothing but accept unquestionably the community’s rules.  As he experiences the memories, he learns that the community is not the perfect world he thought it was.

In The Giver, what are Jonas's feelings towards sameness?

At first, Jonas sees the logic in sameness.  It is even a source of concern for him, at times, that he is one of the few people in the community with light eyes instead of dark ones.  He sees that with sameness, there isn't competition over appearance, or any other issues that cause conflict.  However, as he begins to feel the depth of the various emotions in the memories, and he begins to see colors and things from the outside world, he realizes that diversity is important.  He understands that being unique isn't bad, it's actually good. 

An example of this is illustrated in Jonas's opinions on releasing.  At first, when he doesn't know the true nature of the release, he thinks that anyone who doesn't fit in with the sameness of his community can go and live somewhere else where their personality will be more suited to the personalities of the other people in their new community.  He believes that sameness helps people get along with one another, and that releasing someone who is different is actually helping that person find friendships and connections elsewhere.  Once he realizes that the release is actually a lethal injection, he begins to understand that part of the reason people are released is because they do not fit in.  Anyone who does not fit in, or presents an abnormality, is killed (like Rosemary or the twin baby his father releases).  He realizes then that the community controls the sameness with lethal force, and he questions the cost of this sameness.

Which statements by The Giver show his dislike of Sameness, and which suggest the opposite?

In chapter 12, the Giver reveals that he agrees with Jonas about Sameness when they begin discussing colors and the natural beauty of objects. Jonas mentions that the color red is beautiful and the Giver concurs by saying, "It is" (Lowry, 99). The Giver's short answer reveals that he shares Jonas's view regarding the negative features of Sameness, which include a colorless, uniform world. Jonas proceeds to question why the committee decided to get rid of colors and the Giver responds by saying that they relinquished colors when they did away with differences. The Giver then says,

"We gained control of many things. But we had to let go of others."

This statement suggests the opposite view, that there are some positive attributes of Sameness. The Giver acknowledges that Sameness allows their community to gain control of many things, which help them maintain a healthy, safe environment. However, the Giver recognizes that there is a heavy price to pay for controlling language, genetics, climate, and the natural landscape. When Jonas passionately responds by saying that they shouldn't have changed everything, the Giver once again agrees with his outlook on Sameness, saying,

"You've come very quickly to that conclusion ... It took me many years. Maybe your wisdom will come much more quickly than mine."

This comment indicates that the Giver completely agrees with Jonas's view of Sameness and that he recognizes that there are far more negatives attached to this restrictive policy decision than there are positive results. The Giver is not a fan of Sameness and desires to experience life as originally intended, without barriers or restrictions.