Well, it has finally happened: after yesterday’s IPO Twitter is a publicly traded company. The IPO values Twitter at $25 billion. This is just a fraction of valuation of Facebook and other technology heavyweights, but substantially more than many of the “traditional” companies with a solid reputation and business models.

Twitter has been very, very cautious about setting the public expectations regarding its IPO. The first day valuation is almost twice as big as the one Twitter was suggesting in recent months with its own pre-IPO valuations. It is very clear that Twitter was very eager to avoid Facebook’s IPO fiasco. Furthermore Twitter, unlike Facebook, is still to turn profit. Over the past year or so Twitter has been increasingly experimenting with various advertising models, but in it has even less of a margin for error when it comes to alienating users with intrusive ads then does Facebook.

One thing going in Twitter’s favor is that its micro blogging (or micro messaging) format is ideally suited for the mobile world. Most of its revenue increase comes from its mobile ads, and it’s likely that this trend will continue.

The biggest problem that Twitter faces is that it’s not nearly as user-friendly as other social networks. It’s hard for an average user to see its value, and most people who sign up for it just give up after a little while. Even I am only recently starting to use Twitter more, primarily for the purposes of promoting my writing. (You can follow me at @Tunguz, or at the official Twitter account for this blog, @TunguzReview.) I am learning of Twitter’s potential, especially when it comes to following events as they develop in real time. I don’t think that Twitter’s high valuations are a sign of the new Tech Bubble, and I remain bullish, both of Twitter and its stock.