Firstly, I'll say this: The Crow: Salvation is far from a low-budget knock-off sequel. Most second sequels are restricted by tiny budgets, meaning tiny no-name stars. The fact that they managed to get Kirsten 'Mary Jane' Dunst on board will tell you what kind of budget they're working with here, a pretty decent one.
Secondly, why does everyone hate the Crow sequels so much? Okay granted they're pretty straight reruns of the first movie with different casts, but they look and feel great, and the overall standard of material is pretty high. Plus, I may be blaspheming here, but strip away the veneer of Hollywood Gothic and high-concept production design, and all the original movie really constitutes is an Arnie style revenge flick. Which is quality, I might add, and the next two were exactly the same.
Bottom line with this movie is this: Eric Mabius makes an enthralling third crow, yeah Kirsten Dunst is pretty and all but she misses as much as she hits acting wise and the director knew this so she doesn't spend too much time overdoing the comic book heroine thing. The plot is good, and likeably macabre, so what's the damn problem?
Watch this movie with an open mind and don't think too hard about the original (or do and remember the plot was paper-thin and the characters were really cartoony) and you'll have a blast, okay?