I use it, but not so much.
The 'like' to me, sometimes, has a few meanings: 'Your post was funny', 'I liked what you wrote', 'I agree'...
Maybe if we have a add-on like DBTech Advanced Post Thanks, which we can set new buttons like "Funny", "Dumb", "Winner" would be very usefull!
Nope, if it is not worth a quick reply, but the post I read is worth it, I click like. It's to let the user know I am looking forward to more of those posts. Sometimes it's used as "i agree".
If it's worth a reply, I rather just give a full reply.