My DVD collection actually centres on war movies. I have both films mentioned in the OP. I think Letters is the better of the two and I don't think it glorifies anything. I generally don't care for the films that glorify war preferring the ones that usually focus on the impact of war on civilians. A fact that is reflected in my top five war movies. (Okay top five WWII movies for this thread.)
1.
Hotaru no haka (Grave of the Fireflies)
2.
Idi i smotri (Come and See)
3.
La Vita a bella (Life is Beautiful)
4.
Schindler's List
5.
Letters from Iwo Jima
Only one of these films is in English so if you don't like subtitles I feel bad for you.
These are also not platforms for demonstrating your sound system (except maybe Letters).
The first two are absolute must see films. Grave is the most emotionally affecting film I've ever seen. Many films make you cry yet grant some reprieve at the end. Grave leaves a scar. Come and See is so powerful. I always say it is the only movie that shows real soldiers fighting real warfare. It's about the waging of total war in Belarus. It is also interesting because you can see where some ideas from it were used in movies made since then. The audio effect in Saving Private Ryan where Tom Hank's character can't hear after being concussed. Also the church scene in The Patriot (The Patriot is an outstandingly bad film that should be watched just to see how bad a movie can be).
Some other WWII titles that I recommend. The Pianist, Die Brucke, Kelly's Heroes (seriously, great film), Das Boot (of course), Patton, Ivanovo Detstvo. There are lots.
Non WWII that deserve a look. Glory (American Civil War), All Quiet on the Western Front (WWI), Paths of Glory (WWI), Full Metal Jacket (Vietnam), MASH (Korea) and Seven Samurai. I get flak for listing Seven Samurai but few films make such a poignant statement about military conflict and its effect on both civilians and comrades in arms. It really is one of the best films ever made.
Only anecdotal but a family friend who had been a German soldier through WWII claimed that their preference was to surrender to or be captured by Brits or Canadians. He claimed that American soldiers treated prisoners okay but tended to steal personal belongings like rings and watches. Of course, this was still preferable to the eastern front where they generally weren't taking prisoners.