Grisbi 0.5.5 is a bug fixes release, but it also features a new translation into Brazilian Portuguese from Flavio Henrique Somensi. A new account debug feature has been added (see http://www.grisbi.org/ for details and download)
On the Windows port side, you can now import files in the OFX format (Grisbi for Windows uses libofx 0.7.0 http://libofx.sf.net/ ) and you can use the shared installation of GTK (http://sourceforge.net/projects/gimp-win/) you have done for an other GTK application like The Gimp or Gaim (at least 2.4)
Note that version 0.5.4 has not been released due to bugs. Version 0.5.3 can directly be updated into 0.5.5.