Plus, there’s the dilemma of a retweet of a retweet, and the question of who do you give credit to? (Usually I do both; but, again, space becomes an issue.)

So I think this new feature will be great, especially since one still retains the option of doing a manual retweet if one wants to add one’s own text.

The only thing drawback I can see is that the retweet seems to appear to come from the original tweeter, which, as you say, can be confusing for people who don’t know that person. Also, unless one takes the time to read the fine print at the bottom, they won’t know who retweeted it (meaning that the retweeter won’t get recognized as providing an interesting tweet). (Would be great if they provided a tiny avatar of the retweeter down in the line where it notes their user name.)