Usenet is a worldwide distributed Internet discussion system. While originally designed for text discussions, binary files now make up the bulk of the traffic. Fanzub specializes in indexing the anime & Japanese media related newsgroups and makes these posts available through so-called "NZB" files, which from a downloader's perspective work much like torrent files do for BitTorrent.
What are the advantages of Usenet?
If you get access to a good quality Usenet server, you will most likely be able to download very fast - possibly even max out your connection. Your download speed typically stays the same for each download, no matter if the file is old or new.
If you are worried about getting in trouble for downloading things through BitTorrent, then Usenet is a good alternative. The only party that knows what you are downloading is your Usenet provider, and many don't keep logs! If you are really paranoid, most providers even offer SSL support for fully encrypted downloading.
Leech all you want
Unlike BitTorrent you don't need to upload back to download and there are no ratio's. So leech all you want.
While Fanzub focuses on Japanese media, there is lots of other content to be found too.
What are the disadvantages of Usenet?
Usenet isn't free
Or more precisely, good Usenet providers aren't free. If you are lucky your ISP might provide a Usenet server for you to use, but the retention and completion is likely to be bad. If you want good quality Usenet servers you will probably need to pay for access.
Usenet wasn't designed for binary files
The Usenet system was originally designed for text discussions and each message can only be a certain small size. Because of this binary files have to be split up in several files, which in turn are split in numerous parts. This means binary files posted to Usenet frequently are made up of several thousands of message parts. Without PAR/PAR2 files, missing just one of these parts will impact your ability to complete your download.
Usenet servers can't hold files forever
As terabytes of new binary files are posted to Usenet every day, Usenet providers purge posts that are X days old. While the so-called "retention" time is increasing with the major providers, you will not be able to download posts made several years ago. By comparison, torrents can stay alive for many years as long as there is a seeder.
Usenet isn't great for fansubs these days
Fansubs are usually posted to Usenet by a loyal group of posters. While they typically do a great job, it sometimes takes hours or even days for new fansubs to be posted to Usenet. In addition, there is not as much choice between fansub groups and/or file versions (h264/XviD) compared to BitTorrent.
What are good Usenet clients?
Very powerful Usenet client for NZB files. Can automatically verify PAR/PAR2, unpack and/or join files. Works only through a web interface which might take some getting used to. This FireFox extension and this post-processing script may be of use with this client.
Similar to NZB-O-Matic Plus except with more options.
What are good Usenet servers?
There are countless of Usenet providers. Usually it is best to go with a provider that is located closest to you for fastest download speeds. The biggest providers have server farms in both US and Europe. It pays to compare prices & features to see which one suits you best. Here are a few good providers (Google for more):
Industry leader. If you want maximum speed and retention, you probably want to go with them.
While their site may not look like much, their service is good. What's especially great is they offer pay-per-download accounts in addition to subscriptions. If you don't download a lot, a $25 account could last you months or even years. Their $10 pay-per-download account is a good choice if you want to check out Usenet but not invest to much or subscribe to anything.