Don’t think it doesn’t worth upgrading because 1.4.2 is only one month old. Here are the main new features in 1.4.3 :

• subcell resolution blitting function TCODImage::blit2x
• the long-awaited function that changes ascii, foreground and background colors in a single call !
• unicode support for print* functions along with 4 unicode fonts provided by Mingos
• for mingw32 and linux, the library comes in two flavours to handle properly bad parameters : a debug library using assertions to stop the debugger when a bad parameter is detected and a release library which silently ignore bad parameters to keep the game from crashing

Not that this is still a beta1, so expect bugs and moving features until the final 1.4.3.

The complete changelog is here. Grab the library here.