Would he be considered progressive rock? I suppose so, but whatever you catagorize him as, he is the man. Golden Hours is such an amazing song, it completely lets me know what its gonna be like when I am a senile old man. Who else likes Eno?
I wouldn't consider Eno progressive by definition as applied to genre (only in the literal sense). Most of his work falls under the ambient category, though many of his early albums would be best described as experimental pop. I love Eno's Before and After Science. That's my favorite from him! Tracks like 'Spider and I' and 'Julie With...' really highlight the most provocative aspects of Eno's work.