I really liked NOT being able to see what you get, and having to think carefully, to avoid wasting film. It was always exciting getting them developed - or developing them yourself, if you were that adventurous, which I've only done a few times, at night class.
Although there was always the odd disappointment ("Light was too low after all", or "Damn camera strap got in the way!"), there was the delight of things coming out better than expected, too - sometimes effects you hadn't been planning for.
I still have my old 35mm, and haven't the heart to throw it away. It's amazing what a talking point it is, on the rare occasions I still take it out. Strangers come up to me, and say: "Wow! You still have one of THOSE!".
It's vintage, but hardly antique, dating from around the late 80s (1980s, in case you're wondering
) It's incredible how something that was once everywhere is now regarded as a museum piece, in a little over 20 years.