First, to my modern evangelical ear, he seems to be the most orthodox Patristic writer I have read so far. The letters of Clement are in this league as well while some of the others I've read, all before Athanasius' time, would likely make 21st century American Christians cringe a bit. This leads me to believe that the modern church has been profoundly influenced by him more than most people know.
Second, he is one of the most engaging of the pre-Nicene fathers. He seems to take special care with each sentence. It is evident that he has really thought through the issues. He doesn't come across as speaking only to his 4th century situation but is incredibly relevant and his language is accessible.
Third, and as a counterpoint to my first comment above, though 99% evangelically kosher, he makes two shocking comments that demand explanation by any Patristics scholar. First, in chapter 7 (the chapter's are more like large paragraphs), speaking of the necessity of the incarnation, he says,
"It was unworthy of the goodness of God that creatures made by Him should be brought to nothing through the deceit wrought upon man by the devil... As, then, the creatures whom He had created reasonable, like the Word, were in fact perishing, and such noble works were on the road to ruin, what then was God, being Good, to do?"
Since Athansius commonly uses the title Word of God to refer to Jesus, is he implying in the above statement that Jesus was a creation? Surely not, since in Athanasius' scheme, the incarnation of the word was in fact the solution to the problem. Count me confused.
The other shocking comment comes near the end, in chapter 54, and it is the most commonly cited quote of Athanasius. You've all heard it before: "He, indeed, assumed humanity, that we might become God." My first thought would normally be to chalk this up to ancient figure of speech that I'm missing like when I read a Shakespeare play and only really get about half of it. But On the Incarnation, at least this translation, is easily understood elsewhere as I mentioned in my second observation above. The context is a discussion of the humble means by which God chose to reveal himself, but I don't see how it explains away this strange phrasing.
I'm thinking now that I'm done with the independent study class I've been taking I'll have more time to say more about Athanasius, but for now, I'll leave it at that.