I never thought bz2 was worth it over gzip, but xz is much much better in many common cases (particularly text files, but also other things). Source code can often be xz compressed to about half the size as gzip. If you are downloading multiple things at once or a whole operating system or uploading something then even on slower DSL lines it makes a huge difference IMO. I wish more package systems provided deltas.
The only issue I've had with xz is that it doesn't notice if it is not actually compressing the file like other utilities do and then just store the file uncompressed, so if you try to xz a tar file with a bunch of already highly compressed media files then it both takes forever and and you end up with a nontrivially larger file than you started with.
Also, I like that, unlike gzip, xz can sha256 the uncompressed data if you use the -C sha256 option, providing a good integrity check. Yes, I would really like to use a format that doesn't silently decompress incorrect data and I can't understand why the author of this article thinks that is a bad thing. For backups I keep an mtree file inside the tar file with sha512 of each file and then the -C sha256 option to be able to easily test the compressed tar file without needing another file. In some cases I encrypt the txz with the scrypt utility (which stores HMAC-SHA256 of the encrypted data).
The only issue I've had with xz is that it doesn't notice if it is not actually compressing the file like other utilities do and then just store the file uncompressed, so if you try to xz a tar file with a bunch of already highly compressed media files then it both takes forever and and you end up with a nontrivially larger file than you started with.
Also, I like that, unlike gzip, xz can sha256 the uncompressed data if you use the -C sha256 option, providing a good integrity check. Yes, I would really like to use a format that doesn't silently decompress incorrect data and I can't understand why the author of this article thinks that is a bad thing. For backups I keep an mtree file inside the tar file with sha512 of each file and then the -C sha256 option to be able to easily test the compressed tar file without needing another file. In some cases I encrypt the txz with the scrypt utility (which stores HMAC-SHA256 of the encrypted data).