Growing up on Robotech (Macross) and the Gundam franchise, I have a tender spot in my core for mech anime. If you grew up on said anime, then you have to immediately view this series. It's not for you that I need to make the case. You'll already be willing to finish the series in one sitting.
For those of you, maybe a younger generation, without the mech background, give this a chance. My girlfriend is of the Hunter x Hunter, Kill la Kill, Blue Exorcist generation. But, Knights of Sidonia has your emotional character development, cutesy facial expression (heavy blushing) and the artwork will hold the new generation. I've tried in vain to get my girlfriend to watch many of the late 80's early 90's classics. She loved Ninja Scroll and Armitage, but still admits to not watching older anime for the dated animation. Knights of Sidonia is the perfect oldschool mech vs alien anime with an updated appearance.
For those of you, maybe a younger generation, without the mech background, give this a chance. My girlfriend is of the Hunter x Hunter, Kill la Kill, Blue Exorcist generation. But, Knights of Sidonia has your emotional character development, cutesy facial expression (heavy blushing) and the artwork will hold the new generation. I've tried in vain to get my girlfriend to watch many of the late 80's early 90's classics. She loved Ninja Scroll and Armitage, but still admits to not watching older anime for the dated animation. Knights of Sidonia is the perfect oldschool mech vs alien anime with an updated appearance.