I deciced to set up a twitter account just one month ago, I heard good about and it didn't dissapoint me. I think his popularity is based on his great differences between others social networks as Flickr, Facebook or the Spanish Tuenti. Twitter is more gossip, if you aren't online you miss the information, besides allows you to be in contact with celebrities. Definitely this is why Twitter is so popular and addictive, you feel like if you were the only one who knows this information.
As a future journalist, I find it also more interesting because is actually a journalism tool. I mean you know what well-known journalist think, not with a gossip purpose just to know what is their real opinion, twitter is a quite good way of create your own opinion about the hottest topics. You are allow to know and think about experts', different journalists' and also media's opinion.
Personally I'm quite interested in the United Kingdom elections, those are the closest from a very long time and every single word could change polls or British mind. Last Thursday I wachted the finish of their first televised debate of their history, and currently thanks to Twitter I could find out which are the British media reaction, as I said before there are tiny differences among David Cameron (conservative), Gordon Brown (laborist and PM) and Nick Clegg (liberal) in the voting intention so this debate and two more which are going to be on 22 and 29 of April could be really important. With this example I want to point out the importance of Twitter as a tool not only hobby stuff, without it follow the elections and British papers and journalist would be harder but with this kind of social networks you have almost every information just one click distance.
P.S: If you're hooked on UK election please check the last electoral poll, the outsider (Clegg) could give a great surprise to Conservatives and Laborist. Moreover, his wife come from Olmedo, Valladolid (mi parents region)!! :P