They are significantly safer. Current li-ion in cars have some very bad failure modes; just puncturing them can release a massive, uncontrollable fire that could potentially keep itself going while fully submerged in water. Now, even those are somewhat overblown--they're pretty well protected in cars--but these problems aren't universal to all lithium chemistries, much less all batteries in general.

Yes, they can catch fire. No, you don't need four fire trucks worth of water tanks to put them out. This matters.