Eh not really. Consider my use case. I don't tweet, retweet or anything. My profile is set to private. I mainly use Twitter for updates on the local public transport (and sport scores). Last week for instance the metro system had a really bad failure. At the end of the day, their Twitter account posted a big apology and you could see whoever was manning it had played a blinder by helping as many people as they could. So I "liked" it as a form of appreciation. I do that a lot.
I don't think I'm alone on this either. I know lots of people who use Twitter for practical things (traffic updates etc.), I honestly can't think of anyone who actually tweets though.
If like goes, I'll just use retweet as a replacement to show the same emotion. Except I'll be retweeting to an empty audience deliberately.