Kotiteollisuus was one of those bands who led the new wave of Finnish heavy rock/metal which happened in the early/mid 2000's. Together with Timo Rautiainen & Trio Niskalaukaus they paved the way to bands like Mokoma, Stam1na and Viikate.
Jouni Hynynen writes very good lyrics at times. Kotiteollisuus is heavy and simple, which is why they did reach out to a large audience.
Their best qualities are also their downfall. Lately Kotiteollisuus has been very repeatative, writing the same song/album over and over again. And not in a good way like AC/DC. Hynynen's lyrics are also more often miss than hit. His singing is also quite awful in live situations. But hey, that's rock n roll for ya!
But some of their older stuff is still enjoyable and pretty good.