The concept is alright, nothing particularly intreaguing, but rather than use the concept to do a science fiction love story, it basically used the sci fi bit as nothing more than a simple plot device and went all for the love story. Hence, it feels padded even for 13 episodes, simply because love angst is not ever going to carry 13 episodes on its own.
I believe I said it before, but I felt the background was unbeleivably shallow for the concept. Indeed the one sentence concept is essencially all the background. Hence it felt superficial, no depth to speak of, no...nothing really for me. It had a handful of moments where I seemed it might take off, but they were few and far between for me.