The release contains security fixes, so update from previous versions is strongly recommended.
Some details about the release you find here: ReleaseNotes198, all details you find in the file changelog.txt inside the archive.
You can download the files here: Sourceforge.
Thanks to marc for caring that much about the 1.9 branch, thanks to wog, marc, sylvie, nkoth, luciash, xavidp, sampaioprimo, kerrnel22, franck, chibaguy, mose, jonnybradley, pkdille, ricks99, bluestrain and all the others for their commits to this and all the previous releases.