Invasion is not a bad movie, but neither is it particularly good. I think the enthusiastic reviews are reaching. I will say, it is an awfully strange movie. The protagonists can't figure out whether the aliens are "Chinese" or "Japanese." All they know, or think they know, is that they are - "Asian" - and that apparently there is an alien Asian invasion. It seems like this component of the movie is supposed to lend some kind of air of mystery or exoticism, or perhaps mere novelty, to the story. It's muddled so you really can't ever tell what the filmmaker's intentions were. I would love to read an interview to hear what they were thinking.
In any case, as other reviewers have noted, the movie is atmospheric, has some nice B&W cinematography, and an effective, understated score. Unfortunately the heroic act of Edward Judd toward the end relies on a very weird stroke of luck, which is reflects the unevenness of the script, which is fine in parts but nonsensical in other parts. (Funnily, Judd is just as grim and sweaty in Invasion as he was in The Day the Earth Caught Fire, a far superior movie from a few years earlier.)
Being a fan of 1950s and '60s British sci-fi, it was very much worth the money. While I can't see myself watching it repeatedly the way I do classics like Village of the Damned, Day the Earth Caught Fire, and the Quatermass productions, it is worth tracking down if you like the particular temperament of the classical era of Brit sci-fi.
Fyi: I couldn't find this movie streaming anywhere so I bought a region 2 DVD for 12 bucks, including shipping, from Amazon. It's the Studiocanal edition. (I've included a few photos so you can make sure you're ordering the addition you want to order or so if you get the wrong version you can justifiably return it.) The picture is properly letterboxed at 1:66, which was the standard UK aspect ratio of the time. The picture is surprisingly good, with no blurring of grays and blacks, sharp lines between tones, with the blacks being surprisingly deep. The DVD includes a trailer, which, oddly, is narrated by the guy with an American accent, as well as the smallest photo gallery I've ever seen on a DVD, maybe six or seven pictures. Frankly, it's amazing this movie got a DVD release, so beggars can't be choosers.
