Here are some features of Tweetbot:
Smart Gestures. Use Twitter more efficiently with time-saving and configurable gestures.
Native Push Notifications.
Customizable Navigation. Hide the navigation tabs that you never use.
Support for multiple services like Read it Later, Instapaper, Cloudapp URL Shortening.
Save drafts, add locations and POI’s, attach photos/videos, manage your lists, and much more.
Tweetbot is available in AppStore for $2.99
Checkout this video of Tweetbot for iPad in action: