It works in as much as it runs and does what Modplug's source code tells it to do. Occasionally it hangs (with the only remedy being to do a killall wine.bin in shell) with no obvious cause.

It probably works a lot better with a Wine 2004** release.

Tested:
OpenMPT 1.17RC1 and 1.17RC2 (Generic, Athlon32 and P4/Athlon64)
Under:
Cedega 4.4.1

->hangs on save (major issue)
->may freeze while navigating through tabs

otherwise seems to work as expected and even VST plugins are usable.