Don Bes said:
mikhail himself has said that its not yet quite as good
I think that if you're mostly a Word (= OO Writer) user like me, it's about caught up. However, Microsoft's Excel (= OO Calc) is just plain faster and Powerpoint (= OO Impress) is a bit fuller featured, I think, though not so much so that you'd miss it. If you use Access (= OO Base), the Open Office equivalent is supposed to be woeful - it's not had nearly as much development.
The benefits are two-fold. Firstly, OO is free and staying that way. If you get Office for free, don't bother with OO. If not, it's a nice saving of a couple of hundred dollars.
The second thing is the file formats. Microsoft's .doc, .xls, etc. are all kept private. That's a pain in the behind - you need an M$ product to open
your files. Open Office will open and save to those formats too, though there are some interoperability issues. I've never had a problem with a .doc file, but I can definately see issues if you are a real power user in Excel. That said, the interoperability is approaching that of the various versions of Office (95, 97, 2000, NT, XP, etc.). Open Office has its own file formats too, and can save directly to a pdf file if you want. Its support for .rtf and .csv is supposed to be better than M$ Office's (which seems odd - they'd be hard to screw up).
Anyway, in summary: Open Office is free, but not as good unless you mostly use Word.