Is it worth paying is the big question? Another useful and FREE tool (at the basic level) that I've used is Crowdbooster. In addition to letting you schedule your tweets, it shows you who your most influential followers are, recommends thanking specific tweeple for follows, and has some simple analytics. There are a lot of options on the market, but for organizations or individuals that can't afford a big budget social media strategy, I would recommend trying Crowdbooster. At the basic level it lets you link one twitter and one Facebook account.