Stardew Valley is a masterpiece of a game. It's a great Harvest Moon-alike, but it's much more than that. If I have one 'big' complaint about it is that there are too many things you can do. You can fish, farm, explore dungeons, you can date people and complete quests for a community center. If you want to focus on only a few things - like I did - you'll feel like you're missing out on other stuff to do. That's not a big deal in the grand scheme of things tho; Stardew Valley is a gem that I had a great time spending hours with. There are some little flaws here and there, but otherwise it's an all around success
After a fairly simple but sufficient character creation process, you're sent through the introduction of the game where you decide to leave your job at the big Joja Corporation and go work on a farm inherited from your grandfather. You start with almost nothing but a house and a field in a terrible state, trees and logs scattered around. You have a few quests to tell you how to do basic things like cultivating crops and watering your plants, and then you get into town and you need to talk to everyone which can be a weird chore because people aren't marked super well on the map.
Your character has many stats; farming, mining, fishing, combat and the like. You get small bonuses for each rank you get in them, and at level 5 and 10 you have to choose a bigger bonus that can greatly change how you play your character. There are a bunch of NPCs to interact with, all with their likes and dislikes and you can - probably - marry one and have kids. I didn't touch that system at all, I was too busy fighting, fishing and farming. You sometimes have quests that require you to deliver items to the NPCs, and the map doesn't help there either.
I have some small issues with almost every subsystem of the game, fishing is a bit rough and it's tough to keep the bar behind some fishes that move extremely quickly. Combat is fun, but you can lose a bunch of progress if you die, and it's really frustrating - I restarted days because I died and wanted to keep a strong weapon I would otherwise had lost. Farming is fun but I find the tools to have a weird targeting system sometimes. There are missions to add new features to your town, but you need to go back to the community center to check your progress and sometimes it's hard to know what items you need to keep and which ones you can safely discard. There is a good range of weapons and tools that you can find and craft, but I finished by hoarding everything because I wasn't sure if anything was going to be useful.
The game is also full of new events to unlock and locations that you can initially not get to but eventually - through waiting for the passage of time or acquiring enough wood to fix a bridge, or getting enough quests complete at the community center - and they add new layers on an already pretty complex game where you could theoretically spend each day farming on your own or just go through the dungeon and fight. Maybe you'll have access to another beach or a completely new dungeon, there's always stuff to do in Stardew Valley.
I stopped playing the game when a fishing competition crashed on me and I would've had to restart the day. That was at the end of year one, so I still played a ton of hours of the game and I enjoyed most of them. It's got some minecraft-like qualities, some zelda-like qualities and a huge splash of Harvest Moon everywhere, it's a great game and if any of this sounds good to you, I recommend it wholeheartedly.
