Twitter is a good middle term 5-10 year investment, but not a great long 10+ year investment. I have no idea if it is a good buy with the pricing they have.<p>Twitter reminds me of AIM (AOL Instant Messenger). Back when AOL was a big deal, AIM was how you chatted with people and the network effects of that were incredibly huge. Everybody, every brand, everything was on AOL. Then, the landscape shifted and high speed internet made AOL irrelevant. However, AIM was still around and a lot of people used it for years after they quit AOL.<p>Twitter's big risk isn't the next few years where it's still hugely popular and integrated with media everywhere, the risk is in 5+ years when something else comes along. Will twitter have the staying power of Yahoo, Google, and Facebook, or will it be more of a AOL/MySpace kind of thing?<p>I really have no idea, but I wouldn't bet on Twitter for more than 5 years.