Does this mean look as in visage whereas udsigt is a view from some vantage point? Is there any close translation to sentences like Judging by his look, you can tell he's had a long day.
Yes, "udseende" means "appearance".
For some reason, you can't combine "At dømme ud fra hans udseende," with ".. kan man se at han har haft en lang dag."
You can chose one of the two:
At dømme ud fra hans udseende har han haft en lang dag. (Judging by his look, he has had a long day.)
Ud fra hans udseende kan man se at han har haft en lang dag. (From his look you can tell that he has had a long day.)
What about "he gave me an angry look" would this work be used there?
No. "Udseende" refers only to appearence. An angry look would translate to "Et vredt blik" "Blik" is a noun, that refers to "the look in someones eyes" or casting "a glance at something".