I saw Biophage last month at a friend's villa: it was playing in the background, and two of us at the gathering were sucked in about a quarter of the way through. We restarted the film, and enjoyed it quite a bit.
You'll need to know a few things going in: this is obviously a low budget film. It is, however, a film: shot on film!
I liked this movie. Biophage is a moody piece of cinema. The grain of the film lends itself to the dark subject matter which is essentially, as I see it, the collapse of the lynchpins on which society is built: family, religion, the military, the hospitals, etc. each has a representative in the film: The two doctors representing family are coming apart, wrecked partially by Cain, the main character himself. The military base they find has been wiped out, the Reverend they visit hides a secret (which I bet you can guess), and the hospital they visit to resupply themselves seems abandoned, but is total chaos.
Yes, this is a zombie film (though no one uses that word). It was released in 2010, but from what I've read, it was shot in 2002, and many of its elements, images, and characterizations were still new then. It's a shame it wasn't released closer to when it was shot: it may have been better accepted as a forerunner of a lot of what we see now as "standard zombie movie/TV."
I can understand the limitations of the production. film stock is expensive to purchase and develop, and requires a great deal of discipline while being used. Surely a lot of the budget went to just that: developing the film. From what the accomplished after that on a low budget is good stuff!
All in all, I rate this film an eight out of ten. It has a bit of action, but its virture lies in it being a thoughtful examination of the pillars of society tumbled down, and the effects of that on the individual. See it when you can.