Twitterrific's emphasis on simplicity does have a few casualties beyond its integration with services. Push notifications are nowhere to be found, for example, though the app's description says that you'll get in-app notifications for mentions and direct messages. For notifications while the app isn't in the foreground, you'll need to set up a solution like Boxcar. If you're a fan of other externals services, such as Favstar, you won't find easy access to them here either.
And while Twitterrific 5 does offer gap control, which lets you go back and load all the tweets you may have missed. While it does a good job of eventually loading all tweets, I found that it took more taps to load all my tweets than it did on Tweetbot.
There are plenty of Twitter clients on iOS, but Twitterrific has been around the longest and The Iconfactory's willingness to completely redesign the app every few years is part of the reason the app's success lingers. While Twitterrific 5 features a more competitive ecosphere than ever, there's no reason it can't co-exist along other excellent clients like Tweetbot; there's audience enough for both Tweetbot's industrial design and Twitterrific's more spartan approach.