Not very good. "The X-Files: I Want to Believe" was "phoned in." I ordered it (Netflix) and watched it because I'm an X-Files fan. This was not typical X-Files stuff. One expects aliens or paranormal activity or whatever. All this movie had was a psychic ex-priest pedophile and a Frankenstein-like doctor. I suspect someone thought, "It's time for another X-Files movie. We/I could make some more money on the franchise." But their heart wasn't really in it. So they came up with an idea real fast and filmed it and maybe made some money, but it wasn't very good. It definitely was not up to normal X-Files standards.
Most people go out and see new movies and review them, I know. But I don't go out to see new movies. I wait for the DVD. (In case you're wondering why I review old movies.)