Does what it says on the tin. Accounts are private and there's no invites to hand out (sorry), but no NDAs or restrictions on reporting.
First impression: useful, but there's a learning curve. If you want a specific datum, it's usually there and presented in a a variety of useful contexts. Sometimes information is obviously there but it's not clear how to access it; for example, searching on 'Citizen Kane' will tell me it was directed by Orson Welles (along with other basic data), but searching on Orson Welles just gives the bare biographical data, not his filmography. It's not obvious how to dig that sort of information out.
The computational aspects are impressive and quite accessible thanks to good NLP; if you've already used Mathematica you'll be familiar with a lot of them. I feel like there's a great deal of power that I haven't properly learned how to manipulate yet. I'm looking forward to the aPI, which (per this morning's Webinar) Wolfram says will be public and IIRC, free.
Paid services will include license of the Alpha software for use on a company's internal datasets, as well as for commercial use of the data and 'large' computational tasks (whatever that means).
Finally, it's open to the public on May 18th.
- it IS a preview: not everything is switched on - it's NOT pretending to offer natural language processing for general queries - they're NOT pretending to be a better Google or Wikipedia - I don't know what I'm doing: I'm in Fisher-Price mode, and there is a learning curve.
I am quite impressed, and also confused.