I wish Viserion would have just fell and crashed into the mountains. The fact that the walkers couldn't risk going through the ice and into the water to kill the group coupled with the fact they had to get into the water and wrap chains around Viserion is just so bad. That was my only major gripe because it's just so conflicting with them falling in and being basically worthless during the battle. Oh, and was there a Home Depot where they got all the fucking chains?
I don't think it has anything to do with them not willing to risk going through the ice and into the water. It's just, to them, what's the point? These people are stranded on an island in the cold with limited supplies and are completely surrounded. Meanwhile, the white walkers have nothing but time, as they seem to be immortal, or at least of a significantly longer lifespan than a traditional human. They can simply sit there and let the ice freeze back over, giving them an easy path to the humans, or they can try to attack and watch half their army sink pointlessly.
Further, we can at least assume that it's possible that the white walkers knew that, if they waited long enough, help would come for Jon and his companions, and letting that help arrive may have very much been their intent. The white walkers didn't seem even remotely shocked when the dragons showed up, and they were ready with weapons to use against them. We know that various people see visions in the flames of future events, so it's not outlandish to think that the walkers may be capable of this as well (not necessarily through the flames, but Bran has his own method of seeing future visions as well, and there may be more ways too).
I'll agree that them having the chains on hand was a little silly, but overall I don't really have a problem with their tactic of sitting there and waiting for the ice to freeze again. As mentioned, they have all the time in the world and an army that doesn't require food or shelter. The humans, on the other hand, were slowly freezing to death and would eventually starve as well, meaning that, when the ice finally did freeze, the wights would be attacking a weakened force.
