Liberation Mono is styled closer to Liberation Sans than Monotype's Courier New, though its metrics match with Courier New. The Liberation fonts are intended as free, open-source replacements of the aforementioned closed source fonts.
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Pro Compact line height
Just like Courier New (the metrics of which this font emulates), its line height isn't too big, which results in more lines on the screen, compared to Consolas and several other more popular fonts.
Pro Very readable
Liberation Mono works well with hinting on high-resolution displays.