It may come as a bit of a surprise but I'd never seen this film before. We taped it when it was on TV a few weeks ago and finally got around to watching it today. I tried to watch it once before, many years ago. I rented it from a video library and started watching it. I found the opening few minutes to be excruciatingly boring and decided that I would rather be outside on such a sunny day instead. The video went back to the shop unwatched.
Since today was cold and wintry, I had no such distractions. I still found the start to be very slow and boring. The rest of the film was more like a second rate kids fantasy film, rather than a sequel to the first two films. The alien costumes looked more like something from a low budget TV series. The acting was very poor as were most of the special effects. One the whole I found the film to be very disappointing.