A slow, dull movie.
A movie that feels like a Star Trek script that was thrown out for being too dull. There is just too little going on for too long.
The movie touts that it is based off of the H.G. Wells' story of the same name, though aside from some character names and the title, there is no other correlation.
The sets are cheap. The costumes are unremarkable. The robots are blatant knock off of the Lost in Space Robot and R2-D2, but without the pizzazz. The plot is plodding. Jack Palanace acts like he lost a bet and had to be there.
I'll give the movie that the two female leads, Carol Lynley and Anne-Marie Martin are attractive and the best actors that I've never heard of. Looking them up, they've been in far better movies. Watch those instead.
Also, the explosion is cool.
If you still want to watch it, Rifftrax improves it greatly. Though as they frequently put it, "so bad it's still bad." It apparently has also been done by by the MST3K crew for season 13. I'd suggest picking which group of comedians you prefer and watch that, because watching a second time likely won't be worth it.