Game is pretty good atm and it will only improve.
They fixed most of the bugs. If you like it to be very challenging it is pretty good on Legendary now. Enemies slowly evolve and you get nice screens that show you that. How fast they evolve depends on your actions.
Enemies play like a mix of UFO and X-com ones. By that I mean there are some that just blindside you like in UFO and feel "unfair", especially to newbies but there are also standard enemies that have standard abilities that you just deal with tactically and mostly have control over.
And in DLC2 they added their version of Chrysalids, I will not go into details so I don't spoil it.
Tactical combat is very satisfying now. Game has no irritations from Firaxis Xcoms: no pods, no limited actions, no limited inventory, you can swap items between characters during combat, no % based combat that ignores friendly fire, most cover and other things, characters have multiple stats that are used during combat.
They nerfed most of unrealistic abilities now, your characters are no longer going Zoom Zoom through maps. What is left is partly influenced by Firaxis Xcom and people that just want UFO with new graphics will not get that but otherwise it is pretty cool. Maps are very destructible, you can blow up walls and shoot enemies through the hole.
There are a LOT of status effects and all of them are useful now, both for us and enemies: Dazed/Shock, Disoriented, Fire, Acid, Paralysis, Virus, Bleeding, War Cried, Panicked, Poison (I probably forgot some more). Then you got options like just focus on most damage or blowing up their limbs.
Often you find yourself in situations where each of your next moves matter of you might lose some soldiers but now you got more options then in Firaxis Xcom and it is not all based on managing %.
There is a lot of missions to do, this feels more like playing Long War than basic Xcom. One run can be 50h easily. Now there are all kind of missions, you got scavenge where you need to pick up stuff and get out as reinforcements come in. You got ambush missions where you start surrounded and need to survive 3 turns. You got different kind of story missions based on quests. There are main story quests, main faction quests, DLC quests and secondary quests. There are Haven Defense missions that are kind of like Terror missions but there are also some friendly NPCs fighting alongside you. And there are enemy base missions, those come in 3 kinds: Nest, Lair and Citadel. Nests are unchanged since start, those are caves where you need to kill two control towers to finish it. Lairs got a big overhaul few patches ago, you need to find a Spawnery and get out with all soldiers as enemy reinforcements come in. Citadels also got overhauled, you need to kill enemy Scylla unit but it is a maze with high walls and you need to fight through incoming Pandorans until you get into contact with it and then get out after you kill it.
Geoscape is also pretty cool, there is always a lot of things to do. Some of those are connected and some are not. Compared to previous versions you are now not swimming in resources and you need to plan how you play which makes it all very interesting, especially since now you cannot scan from your airships but only from scanners that is a base building (like of UFO). You don't search for enemy craft but Points of Interests or enemy bases.
Soldier customization is also pretty cool. You got 3 body slots and each of those got their own mount slot. Base game lets you mutate your soldiers in different ways (it replaces one of the 3 body slots with a mutation) and DLC1 brought bionics that works similar to mutations but you put in mechanical parts that give different bonuses and has different weakness. Then DLC2 brought in special weapons that are not easy to craft but are pretty powerful and fun to use. And then choosing soldier skills is cool, you can freely multiclass and make any combinations you think can work and you get a 3rd row of random perks that you can also try to make a character around. There are weapon proficiencies but anyone can use any weapons (but they get accuracy penalty). And anyone can use any armor. Only few armors have additional abilities that you need proficiency to use well.
There are still some problems that devs plan to improve in future. Things like more UI improvements are coming, better AI for enemies, some missions might get more rework or improvements. Vehicles will get more improvements. Research and diplomacy will probably get some improvements. They are also testing systems to improve animations speeds and how to make modding the game easier. And whole DLC3 with enemy air units and crafts and some kind of air combat that should also come before Steam release.
Current state of the game is of a 8/10 game and once they are finished with all these improvements it will easily become 9/10 game.