I've never really cared for them. As far as the ferrocium rod goes, that's OK but I've always struggled with getting a decent amount of magnesium filings scraped off to do any good. For me the time spent making a decent bird's nest of natural tinder outweighs the effort to scrape the mag block and gather the filings. The greatest thing the mag block is in my mind is that it provides a convenient holder for the ferrocium rod and that's about it.

JMHO, to each their own on this one. There are other fire starters out there with other types of tinder (cotton balls /w vaseline, dryer lint, commercial tinder, etc.) that are more worth while than the mag block. If it's the ONLY thing you have, then you make do with what you have. Otherwise plan and use your best tools.

The other fire starter I never really found much use for was the fire piston. Yes, it does work, yes it produces a small amount of burning embers but the amount of ember is small and is less valuable that other fire starting methods but again, it its the last thing you have, then you make do.