The first film was good, each successive entry into the franchise has run the range of quality from 'just a bit disappointing' to 'beyond laughably bad'.

Blade
Highlander
Starship Troopers
Halloween
Friday the 13th
The Crow

These are the one's which pop into my head first.

Any others?

I've excluded Hellraiser as Hellraiser 2 is the best of all of those.