Like any film you generally enjoy, it's easy to overlook, forgive, or try to rationalise it's faults. The dune buggy scene and B4 discovery are dumb and contrived respectively, personally I find the fact that they could have just turned the bloody lights up when they were being boarded, and the crappy fight that Riker had less forgivable.
Objectively, it's a poor film in parts, but the opening scene, wedding, end battle, solid FX and generally adult tone outweigh it's problems for me. I realise I'm in a minority though.
Is it unfairly criticised? Yes, I think it is, to a degree, the things it's pulled up on are generally very valid criticisms, but I don't think it's anything like the horror show it's made out to be.