Has anyone used or heard anything about Optimus camping stoves?
If yes, what is your opinion on them?

www.optimus.se

One of the top brands out there.

I have the Crux and it's excellent.

http://www.optimus.se/index.php?option=com_content&task=view&id=12&Itemid=65

i have one and used to own several one's. The more classic models like the 123r, 8r, 111, etc are known and praised for there reliability and are basically good workhorses.

The newer models are more hightech, but very well designed, easy to maintain and use. They use a little to none plastic, so they are also more durable. Optimus and Primus are mine favorite brands, because of that.

You may wish to poke around this site. http://www.spiritburner.com/forum/

Optimus stoves were the gold standard for many years. I own 40 or so various models made over the years. I've never been unable to get one running in the bush, can't say the same for several other brands.