Twabbit's overall performance in commendable, with fast app start up and speedy timeline and tweet loading. The app's main panorama is divided into three pages: home (timeline), interactions (mentions) and inbox (direct messages). From the main panorama you can drop into profile panoramas (profile, tweets, favorites, followers, friends), tweet details panoramas (tweet, conversations) and quick reply (or quote) pages by tapping (or multi-tapping) on a tweet, a username or profile picture as appropriate.
The UI largely follows Metro guidelines, with the usual emphasis on text size, colours and spacing to create a chromeless layout. There's some nice touches such as the use of mini-icons to indicate the presence of meta data such as associated images, location data, or whether the tweet is part of a conversation. A similar example is the use of mini profile images in the tweet details page in line with @ mentions in a tweet.
Twabbit has decent media support with image uploads to Twitter, TwitPic and yFrog and picture previews (in tweet details pages) for Twitter, TwitPic, yFrog, Instagram, 500px, Pinterest, EyeFM and any url ending ina .jpg or .png.
Also included is background agent support that updates the default account in the background, though as with other Windows Phone Twitter applications there's a limit to what it can achieve due the platform limitations.
Particularly impressive is Twabbit's gesture and customisation system that allow you to specify the way the app behaves. You can set what happen when you tap on a tweet, username or profile picture; specify the action for a two finer tap on a tweet (e.g. compose reply, reweet, or quote); and configure a shake gesture (e.g. refresh timeline).
The end result, assuming you can remember which gesture you applied to which action, is a user experience that allows you to get what you want done, faster, with fewer steps, than other Twitter clients. Other Windows Phone apps have used this type of interaction model before, but Twabbit stands both for the number of gestures supported and the comprehensiveness of its customisation options.
Other features of Twabbit that help keep the focus on a fast user experience include a persistently present new tweet button (available in the top left hand corner of the screen from anywhere inside the app) and a quick reply bar for swift replies when viewing a tweet.
Those with large friends list and a large signal to noise ratio will also appreciate the "under the hood" mute feature that lets you block specific users, social apps, or hashtags from your timeline.
Twabbit can be downloaded from the Windows Phone Marketplace. The free, ad-supported, trial version is fully featured and unrestricted, with an option to upgrade to the ad-free version for £0.79 / $0.99 / $0.99.