Combat seems perfected and deep, the RPG elements look good, and to my understand theres TWO ways to gain XP/level up, and then theres your weapons, lots of different kinds, and your effectivity with the weapon depends if the weapons level and your skill level matches up. Also theres of course items, throwable weapons, and as demonstrated in the video, special items (for example earrings work better with magic etc).
Not to mention that there are four playable characters including Relm. Anita, a witch, Shaska, a dark-skinned rogueish character, and Guntz/Goldo (I don't really know which name he decided to use), a male warrior with an awesome berserkery portrait when he goes brute. There are now four factions for you to gain/lose points in as well, using the same kill/save method from the first game. Two different kingdoms, one blue and one red, scoundrels (like the male humans in the first game that were aggressive), and monsters. The addition of the kingdoms comes with a few extra human-type characters being added for a total of ten different humans per red/blue kingdom, five male and five female. Those were detailed in his last videos. He also mentioned a few new monsters while he was showing off the new features of the succubus enemy, including an incubus, but he's yet to show any new monsters apart from the female version of the zombies from the first game and a new dragony boss. And Miku as a boss, but I think that was a joke and I doubt she'll be included in NS0 when it's released. Tragic.
He's also got the opening finished, which you can see in the next-to-last video if you have a Nico Nico Douga account, and has showcased the two shops, General Store and Blacksmith (complete with machine-generated English voices to make them resemble the shops from the old D&D arcade games), the former of which sells weapons, armor, accessories and consumables (and orbs o.o I hope those don't stay buyable) and the latter of which upgrades weapons. Weapons can be upgraded in a lot of different ways, lowering and raising five different weapon statistics and the weight of the weapon. It's only natural that the combat system uses all of those as well. Like fedfyr said, it's been perfected. :D Different weapon skills now use ability points instead of ability spheres to learn, which are gained on both a per-weapon basis (points usable only on skills for the weapon you earn them with) and a 'general' basis (points that can be used on any weapon skill). Aaand.. That's about all I recall offhand.
Anyway. If he's got as much finished as it seems he does, all that's left to do is making the maps, finishing the story and balancing everything afterwards. While I have no idea what his release plans are/if he plans to release a demo or something, the amount completed is still great news for those of us who have been stalking Mickman for updates like myself.