I have never played GC2, but I think I can answer a question or two though.
This brings me to my question, is Galciv3 currently in a state comparable to Galciv2 that it is worth getting? A lot of the research and googling I have done say the game is buggy, there isn't any Espionage yet(A complete deal breaker for me)
Last I checked it is on the ToDo list for the expansion next year.
the AI is actually worse, etc.
Well, it's good enough to have someone ask how to beat it on normal every now and then. I won't say it is great, but you can nurse it up with some mods (copy a folder and check an ingame option - done). So it is not bad either.
and from what I have read, a worse interface.
The two bad UI things I can think of would be the economy wheel and starbase modules. The first one was bad when it was beneficial to micromanage all planets - you don't need that vs. the AI and doing so wrongly has drawbacks now. The second one was bad when you had to order all modules for all bases separately, there is some automation now.
Is the game feature complete, or are there certain things that won't show up unless you buy DLC?
Hmm, let me think... A couple of things are actually DLC:
- map editor and some preset maps (Map Pack DLC); if you are into randomly generated galaxies and not into using the editor you are fine without it
- factions (Mercenaries, Revenge of the Snathi and Rise of the Terrans DLCs) from what I can tell, the RotT faction is not really worth it, the others are a fine addition
- ship style sets are on multiple DLCs, like the three mentioned in the point above.
- Campaign Missions; Some are in the base game, some side story lines are in DLC (mercenaries, Snathi, RotT, Altarian Prophecy); you have to know if you need them or not
- Parts for the ship builder; I would only suggest it if you realize you really enjoy building ship styles; take a look here, for what you can do with ship building
- Precursor Worlds DLC - additional planet types (more building space but lower max population); I am fine without them.
- mercenaries (Mercenaries DLC) - More or less buyable hero ships with some effects that are not obtainable via teching; an option I feel I am playing too little with, despite being an interesting mechanic.
- Lost Treasures DLC - new colonization events, coupled to planetary improvements and /or ship components; I like it. Partially deals with the lack of ideology points on smaller maps, too.
- Mega Events DLC - Some Mega Events are in the base game, but the best ones of course are in the DLC.
In short: you don't need all, but some (at the very least Mercenaries) are worth it in my opinion. SD is also still actively developing, so I suppose there is a bunch of DLC to come. Some features (e.g. asteroid mining) also find their way into the game with patches for everyone.
Should I just play Galciv2 and wait a year or two until Galciv3 is more fleshed out, or is Galciv3 worth a purchase now?
I have bought GC3 more than a year ago and have since sunk a couple of hundred hours into it. I'm happy with the purchase (then again I can't compare to gc2).
I'm not sure what is gonna happen in terms of money investment with the expansion "crusade" next year, which will be a standalone, but given how pricing worked on the Elemental series I am not too concerned, actually. There are worse than SD out there.