I have a similar one. Only maintenence is to change the water pad about a year, about $10 or $12 and takes 5 min. There is a small restrictor in the water line that can get clogged if you have hard water but that's easy to clean.
more info:
http://ths.gardenweb.com/forums/manuhomes/
No personal experience but I have been doing a lot of reading about home building (actuall building my home now). From what I read, modular houses don't appreciate as fast as a stick built. Resale is also less compared to a stick built...