I have given the overal package a 3 star rating, but I will also rate the films individually as follows:
This film is a classic, from the pace, the humour, and the action to the good cast and the story. Terry Mann is awesome as the bounty hunter 'Ug'.
A good sequel which adds more to the story and overal I found it equally as entertaining, although not quite as good as the first film.
Critters 3 was an alright film, the lack of Terry Mann (apart from the end of the film) hurt it a bit, but the character of Charlie was a good one to focus on, this isn't a bad film, but didn't quite have the grip of the first 2.
Unfortunately, this is the only film in the series I found very below average. There's not much screen time for the Critters at all, and destroying an established character for no good reason seemed ridiculous. You can see why this one stalled the series.
The first 2 films are fantastic, the third one is alright for a rainy afternoon, but the 4th is really only worth watching once if at all.