Quite a few advantages to nftables. I have been advocating for people to start learning it now instead of later. One of the primary issues I have seen in systems from a sysadmin perspective is poorly configured iptables. I disagree with all the abstractions that make it "easier" but result in more misconfigs. Besides improvements I expect to filter back over to linux from the dragonfly bsd netstack, nftables is one of the biggest moves in a while. Next up, routing engines like Cjdns, but that's a different discussion.

From the nftables wikipedia:

"...iptables firewalling code, which has protocol awareness built-in so deeply into the logic that the code has had to be replicated four times—for IPv4, IPv6, ARP, and Ethernet bridging—as the firewall engines are too protocol-specific to be used in a generic manner.[10]

The main advantages of nftables over iptables are the simplification of the Linux kernel ABI, reduction of code duplication, improved error reporting, and more efficient execution, storage and incremental changes of filtering rules. Traditionally used iptables(8), ip6tables(8), arptables(8) and ebtables(8) (for IPv4, IPv6, ARP and Ethernet bridging, respectively) are intended to be replaced with nft(8) as a single unified implementation, providing firewall configuration on top of the in-kernel virtual machine.

nftables also offers an improved userspace API that allows atomic replacements of one or more firewall rules within a single Netlink transaction. That speeds up firewall configuration changes for setups having large rulesets; it can also help in avoiding race conditions while the rule changes are being executed. Also, a planned compatibility layer is going to provide translation of already existing iptables firewall rules into their nftables equivalents."