I always enjoy it when people leave comments. It’s nice to get feedback and particularly nice when it’s positive feedback. However, if you do plan to leave a comment, please try and make it relate in some way to the post or page it’s connected to. Don’t just leave a “This is great!” or a “Really enjoyed this post.”
The problem is that I get a fair number of spammers leaving comments, and one of their techniques is to machine generate generic positive comments on random posts. I’m guessing the idea is that I’ll approve the compliment without thinking too much, after which they’ll have an approved identity to use to create immediately viewable public comments on other posts.
So if I’m in any doubt I mark generic comments as spam. Only if I see that the comment was clearly generated by a human who actually read the post do I approve it. I’d hate new commenters to feel I was deleting their input, but I’d hate to get smothered in spam even more.