Twitter is a tool. Like any other tool it depends on how you use it. You can use a hammer to scratch your arse, or to build a house.
I use it for various things: work, sport, news, gossip and entertainment. It pays to invest a bit of time in it. It's not 'just like Facebook for celebs'. You can use it as such if you want, but you're missing out on a lot if that's all you do.
I used to be sceptical of twitter.. but it is now a source of great entertainment, trust me. If you only follow one person, make it Todd Barry.
If you follow a couple more, make it Chino_Wanker, KnobheadLiam (Gallagher) and MY_MUMS_COLA - it's worth just reading their back catalogue of messages from the start.