I love them, and use them. Of course, for the PC who has one, it's one of about a half dozen magical weapons and more than a score of mundane weapons he hauls around. Pays to be prepared. It's also a function of play style. My personal play style emphasizes saves over AC and HP. I take advantage of multiclassing, distribute my stat points to improve saves, and I'm much more likely to jump on the resistance item than the deflection item. For somebody who plays differently, the luckblade wouldn't be as appealing.