I plan to upgrade my laptop to SSD and I want to know if its worth it.
My current HDD is 250GB, from which 50GB are free and 80GB are videos downloaded over 3 years. I don't think I'm a heavy torrent user, but I'd like to know your advice if should replace it with an SSD of the same size. Usually they dont recommend storing large files or big applications on an SSD.
depends.
with an ssd (i'll assume you are talking about the flash variety), while the reads are unlimited, the writes aren't. with torrenting, if you aren't saving a lot and writing over stuff a lot, don't sweat it. if you are... you might not need to worry about it that much... the ssd drives even out the writes so that the writes are spread around, increasing longevity and even regular daily writes won't cause the drive to fail for years (that's a speculation since it's hard to tell).
a lot of drive manufactures claim that you can write multiple gigabytes of information every day without fail for years (ranging from 5 to 28 years). the wikipage has tons of information.
http://en.wikipedia.org/wiki/Solid-state_drive
as far as not recommending storing big applications and large files.... it depends on why they aren't recommending it. i keep all my applications on the ssd and use the magnetic drive for torrents since i'm constantly writing over them... and i have a lot of them. if the primary concern is to avoid large chunks of data spread out across the disk, yeah i can see that since you don't want to defrag an ssd... but the reads are so fast and there are no moving parts i doubt it would matter.