For whatever reason, it’s clear that Twitter want you to use ‘new’ style retweets. They are better for analytics and data-mining, and lower the barriers to participation for unseasoned users.
However, if you’re like me and prefer old school retweets you may be annoyed that the so-called #NewTwitter makes this rather hard. If you want to quote someone’s tweet and add your own anecdote, you’ll have to copy and paste the tweet and then type out the “RT @username” part. It annoyed me enough to make a JavaScript bookmarklet to solve the problem.