We'd expect you to do a clean install or upgrade of the OS software, give your feeback on the install process, make note of changes since the previous version, take some screenshots, evaluate the benefits of the new features and capabilities, and perhaps give your impression after using the OS for a couple of days, if that's possible.
Reviews don't have to be long, as long as they're thorough. We're interested in reviews of new versions of major OSes, major releases of niche or hobby OSes, reviews of groundbreaking software that's important in the alternative OS world, reviews of new computer-like devices (e.g. new PVRs, internet refrigerators, game consoles), or anything else that might interest OSNews readers.
We'd also like to publish book reviews. We can get free books for review, but in order to keep on good terms with the publishers, we have to be very sure that if they send us a book, it is read and reviewed.
If you're not a native English speaker, or you're just a bad writer, don't worry. If you write the review as best you can, I'll edit it, or even re-write it for you before it goes live.
If you need some ideas, some upcoming releases are: Mandrake, Fedora, SuSe, Panther, Zeta, OpenBSD, FreeBSD and Java Desktop System, while recent releases involve Lycoris and Windows Server 2003. If you're interested in one of those, or any other, please email us as soon as possible so we can make arrangements to have an evaluation copy of the software sent to you, while other OSes are free to download (if you don't have the bandwidth to do so, we can burn and send a CD to you).
If you have any questions about OSNews' general submission policy you can read it here. It is highly suggested you read this document before you submit your review.
Note: To ensure real-world testing, operating systems should be installed and reviewed on real partitions and not via runtime engines/emulators like VMWare, Bochs, VirtualPC or Mac-On-Linux (except if you are reviewing the emulators themselves of course).