Twitter mobile web app looks and feels much like the Twitter Android and iOS apps. It looks gorgeous, I've got to give credit to Twitter's designers for that. Will I be using it? Probably not that much. I'm a big fan of the "old" editabe re-tweet, which Twitter discourages. Traditional editable retweets are still availble in the iOS and Android versions of the Twitter web app in the form of the "quote tweet", which is essentially an editable re-tweet except that instead of using the "RT" convention, it wraps the original tweet in quotation marks. On other platforms including Windows Phone, Opera Mini and Synbian the editable retweet is nowhere to be found.
There are some some pretty big paradigim shifts in the new design. The old "Mentions", "Favs" and "Messages" tabs are gone, replaced by "Connect", "Discover" and "Me".
I think the new organization generally makes sense, although it will some getting used to. However there are two areas where I think the new Twitter is harder to use than the old, DMs and hashtags.
In summary, the new mobile Twitter Web app looks good. It seemed quick and smooth on my Nexus S 4G. But with lack of editable re-tweets on some platforms and serious usability issues around hashtags and DMs I think I'll stick with Dabr.com.