The DLC mp modes are pretty good I hear. Haven't tried them yet. But if you liked 5 at all then you should have fun with this. It controls a lot better and playing alone is better now with the changes to your a.i. partner. Leon's campaign alone is worth $20 if you liked numbers 2 and 4, imo anyway. Plus it has a lot of options and actually had an update that changed it quite a but, imo.
I'm sure there will be a "gold" edition soon though with all DLC for $30-$40 but getting it for $20 and buying all DLC is probably cheaper or close to.
Definately a good game. Dont listen to the reviews. Also when your game is patched make sure to set the camera settings field of view and view while aiming to 15. Trust me, it makes the game alot better than the default camera.