I don't know what it is about this font but it doesn't feel monospaced. Using this font I constantly keep second guessing myself as to where I've placed whitespace. Maybe I just need to use it more, I don't know.
Glancing at it I'm not sure if I would immediately be comfortable with it - it's a much narrower glyph than the type I'm used to. I think the lower width:height ratio is part of your whitespace issue, combined with the seemingly liberal kerning.
Exactly this. Maybe if I'd be staring at it for days it would be ok, but right now it feels uncomfortable to read, to the point I'm probably not even going to try. Then again, just like the other commenter I always come back to Consolas or something so similar that it's hard to distinguish.
On a sidenote: what is the font is this textbox I'm typing in?