The Meraki ACL situation is best compared to a VACL. It works on switched packets so it can block traffic between hosts in the same VLAN.
So it has one long list of entries that work on optional source VLAN and L3/4 info. So it's quite easy.
However it comes with a big downside for me. It only allows 128 ACE entries for the entire network. Since ACL's are stateless and you can have many VLAN's that list fills up very quick even if you keep it quite basic.
If you need more room for ACE's I would recommend going for a more hybrid approach where your coreswitches are Catalyst and your access switches are Meraki. You can now monitor Catalyst switches in dashboard so it's a valid design to have for example 2 9500's as core and a bunch of stacked MS250's in the access layer.
You also have the ability to use adaptive policy which basically is a Meraki version of Cisco Trustsec, however you need all MS390 switches in your network in the access layer and they are at the moment still a bit finnicky.