So I love Sunless Sea and this looks good but how is it? In terms of content, bugs, ect?

A bit hard to say since it's clearly not finished yet. I've only played it for a little bit so far. It currently looks very like a Sunless Sea 2, which is both a good and bad thing as it doesn't have its own identity yet.

-World is a bit barren right now, but that's to be expected.

-Starting train moves a lot faster than your previous starting ship and feels more maneuverable in general.

-Upon leveling up you choose from a number of facets with different stat bonuses and story hooks. This part looks promising.

-UI is a lot more colourful. Also, when at a port, rather than going through dialogue branches to get to a certain location, you now pick where you want to go from a tab.

-Combat I haven't tried yet, but it looks like you have more avenues of attack.

I still feel like they could ditch fuel and supplies without losing much and use the room this gives them to focus on deepening various aspects of terror and utlising trade as a story tool instead of a supply hunt. Juggling fuel an supplies feels like it detracts from the more interesting aspects of the game and doesn't create exciting situations, unlike terror - you either have enough supplies and fuel to keep going, you're dead in the water. I'd recommend getting rid of them.
Other than that, it's hard to judge how good it'll be since I've been avoiding finding out what the plot is like.

First of all, game is a little buggy and the world is barren. However it is more colourful, the ship (train) is way faster and more responding than in sunless sea and your crew doesn't eat all supplies as fast as in sunless sea. The fighting is also way faster and more rewarding, as you don't have to wait so long before you can attack.
As I have really enjoyed the story of sunless sea, not its gameplay, I am pretty sure that this game is better, albeit still in early acces.

Personally, I Know i'm not the one asked to, but I find the tab system more convenient than the one in Sunless Sea, rather good change.

I liked the convenience, but I did feel that having them be accessible upon arrival took away some of the mystery of exploring a new location and made those sections feel more separate than connected. What I believe would work better is to have the obvious locations unlocked immediately and have the rest become active upon reaching them through a dialogue branch, maybe with the tab greyed out and inactive until then to hint at what hasn't been explored yet. This keeps what the character learns and what the player learns on equal footing and therefore from becoming gamey (how did the character know where to go when we just arrived?), while also giving the player a sense of exploring the place instead of teleporting from scene to scene.

As it is, from what I saw the tabs don't feel 'connected' to each other yet, though I can see it working well if slightly changed in this way - transitioning from being new and still looking around, to being familiar and knowing where you want to go.

You're welcome. :) I hope it was helpful.