Pretty simple mission, with a bit of nostalgic emotion.
The Normandy Crash site is identified, you scan the planet and beam down. You view a cutscene showing the Normandy debris among chunks of ice and snow.
The majority of the mission is collecting the 20 dog tags, these are scattered around the small-ish landscape, and are fairly easy to find if you keep an eye out for the hud outline or glow.
There are some emotional parts, you see main parts of Normandy completely destroyed, they show a flashback image of what it used to look like, or the character that used to be there. I don't really want to spoil this, but for me I gained some insight into one of the characters, and it made me appreciate and respect him more.
You then plant the memorial for those who lost their lives.
A pretty standard mission, no combat, just item hunting.