I remember Devil Dog playing on TBS almost 20 years ago, and my older sister and her friends watching it and laughing all the next day. It's not that bad for a made-for-TV horror movie, but it is derivative (mostly of The Exorcist) and businesslike, for lack of a better word. It won't blow you away with artful cinematography or great acting, but it's not a waste of time, either. It's the kind of movie you watch to kill a couple of hours when you aren't in the mood to think too hard.
However, if you go into the movie looking for some laughs, you won't be disappointed. The early scenes, with Lucky the Devil Dog as a cute little puppy with Children of the Damned eyes are hilariously non-threatening, and the climactic blue-screen effects of a giant black dog (with horns!) are pretty side-splitting. And keep an eye out for the cloaked Satanist in Maverick shades toward the beginning.
Not a great horror film by any stretch of the imagination, but I wish they still made stuff like this for TV.
