It feels like a port, but a well-done port without many of the offensive technical issues that other ports have (like running mouse/kb input through an analog controller emulator, UGH).
One example: The same button used for run, take cover, jump over obstacles, skip dialogue, and select answer. This is an issue with console controllers requiring multiple mappings due to lack of buttons. Why this is bad for PC games is mainly because you'll want to skip dialogue and wind up accidentally selecting a dialogue answer you didn't want.
Another is a lack of content. There aren't many missions that deal with the main storyline, and those missions take only 10-15 minutes each. There also aren't many side missions / plots... and those there are also last only 10-15 minutes. If that. I would've loved to have seen more missions, and lengthier maps. My gut says that more weren't included because of console limitations, or maybe they figured console gamers don't have the attention span to do that many missions? Dunno.