Ringo: yes, Hans-Christian Blech is in 08/15, and Wolfgang Preiss is in "Hunde, wollt ihr ewig leben" (both actors appear in The Longest Day). The only similarity between the Stalingrad movies is, well, Stalingrad. And you can't avoid it being a unit picture. Since both films view the conflict from the German perspective, there are similiarities as well.
I rather enjoyed "Enemy at the Gates". It is not a film about Stalingrad per se, but about the "private" battle between two snipers. So of course the film can't (and doesn't want to) do justice to the battle as a whole. It's done by Jean-Jacques Annaud which we consider just one of the greatest European directors around. I had a long talk with him, in 2000, about "Enemy", and since the theme of the film is really how legends are made, and how the public is made to believe in false legends, we were also talking about the influence of Ford on himself which he could not deny. As a joke, he finally signed a photo to me with "If the Legend becomes fact..." A very intelligent man and fascinating filmmaker.
Try to catch "The Bridge" (Die Brücke), it is considered one of the best German movies ever, and one of the very best anti-war-films. The b/w photography is striking. It was this film that enabled its director, Bernhard Wicki, to direct the German section of The Longest Day. You'll recognise the same actor from the early Stalingrad movie in it, Günter Pfitzman.