I personally like darker colors, but there’s not enough contrast for easy reading. Someone with poor eyesight would have a really hard time with this, even if they bump up font size.
Font choice isn’t conducive to easy reading. I don’t hate Courier New, but find it better for headers, rather than body text. I’d probably try a sans-serif font, like Verdana or Tahoma as they’re easier to read on screen.
Icons are also dark and muted. Fits with the style, but they lose functionality and become more a design feature, in my opinion.