Silent Running (1972) - A Sci-Fi low-budget "classic" that I personally found extremely overrated

I like to watch sci-fi classics, and last night I sat down to watch Silent Running (1972). I had gotten this film a long time ago, after I had found it recommended somewhere in internet. I love many of those classics like Colossus, Forbidden Planet, 2001, etc. But I found this film disappointingly boring, with an old-fashioned acting performance and the end was uninteresting.