A few thoughts: Witness a walking pot farm zap itself on an electric fence! A meteor shower causes most of the population of Earth to go blind and drops a sort of alien flower/spore that spreads and kills people. How about that for a campy sci/fi horror premise? By causing this mass blindness, the movie finds a way to demonstrate how panicky and selfishly exploitative people can be, which I found very clever and well done. But let's talk about what brings people in and makes the movie special: the giant killer alien flowers. They're pretty cheesy, but I mean, what else would/could/should you expect? This isn't high art, it's a movie about evil alien plants that walk around (or I guess "scoot" would be more accurate) and kill people. The plot meanders at times, but the special effects work is great in that goofy '60s sort of way, so I can forgive a few pacing issues. This movie delivers on its promise and doesn't leave the audience feeling cheated by a lack of triffids. There are plenty of triffids, don't worry.
Who would I recommend it to? Anyone at all who thinks a plot like this bears promise. It's a weird '60s sci/fi cult classic.