These table mats are very asthetic and add a but more luxury than others but being natural materials They do have a few downsides. Not all of the mats are completely flat (there is a bit of wobble in them unfortunately) ... this was highlighted to the seller and they resolved. 
As you can imagine, these are natural and raw slate, therefore they will chip and fracture around the edges if not handled carefully, they can also be quite sharp, so best not for use with kids.  

Make sure you wipe them down well after each use as they do show water stains and spillages very well. But with a good wipedown they are good as new.