The 599LMR is working well. It's using an SiS 530 plus 5595 core chipset, an SiS 900 10/100TX PCI LAN, and a C-Media 8738 4.1-channel PCI audio plus softmodem combo chip.
It isn't fast, but well fast enough for normal, non-gaming home or office computer use. Even the CPU driven modem is useful, connecting regularly at 50k and above, and leaving enough CPU power to other tasks so that Internet browsing works neatly (even with the cheapest Cyrix processors you can get). All the integrated stuff, VGA, sound, modem, and LAN, have good operating system support. There are mature Linux drivers, even for the softmodem, and SiS even has recently released Linux drivers for the DVD decoder hardware (just in case you want to reduce system cost even more by not buying a commercial OS). PC-Chips bundles Corel Linux and Wordperfect Suite with these mainboards.
Being MicroATX, it eliminates most of the ribbon cable and slot bracket mess that its BabyAT relatives M598LMR (same chipset) and M585LMR (VIA MVP4) bring.
Regards, Peter