Hello!
I have seen a few reviews of the game and consider buying it, since it is on a sale.
But I need to know a few things and I hope that the members of the community will help me out.

1. Does the game still get updates (on GoG or somewhere else) or is this the final product?
2. Is the game in its current state playable?
3. Is/has been the developer responsible towards the game and have they kept attention to the community's needs?

One bonus question:
4. How heavy is the game, in relation to mechanics? Is it difficult to get into (something like Dwarf Fortress where you have to watch hours of videos and read dozens of pages of documentation to learn) or is it a simpler experience?

Thanks to anyone who might decide to answer the questions.

To answer your questions:

1. No, it's been complete for quite some time. Gog is fully up to date, we're not behind patches or anything.
2. As far as I am aware, there are no bugs in the game as it now stands - at least none that I have seen or heard about. It's possible to play through and complete in a number of ways.
3. The dev has changed some things, early on - mainly bug fixes from what I can gather. It could be argued that there's room for quality of life changes, but that would likely require a redesign (the UI can be somewhat clunky, but that partially stems from the fact that it's possible to rearrange your inventory. There is an auto-arrange button which works fine for the most part though. It's also clunky because of the significant flexibility of the crafting system - in general, if an object can function as a stick, it can be used in crafting recipes requiring a stick).

4. The game is pretty damn brutal. I didn't bother with gameplay videos, because I hate watching other people play things and that takes too long, but it's definitely worth heading to the game's website, forum and/or guides to get some survival tips if you find yourself getting frustrated. That said, dying many times is one of the game's charms - you're not a hero in this game, as even if you create a combat-focused character, you could still get wiped out by a guy with a gun if they manage to shoot you in the head. There are ways to mitigate danger of course - which usually boils down to "don't fight something more powerful than you unless you're well prepared" - and even then you might still get killed.

It is most definitely a brutal game, and you will almost certainly die many times before you "complete" it. But making it through to the end isn't really the fun - it's all the stuff that happens on the way. You can easily ignore the plot forever if you just want to hunt in the wilderness, for example.

Finally, you didn't ask this, but know that the game is moddable (one of the things added by the dev after request), and there are a number of mods around, most of which change the crafting (in theory, you could invent entirely new objects, and invent crafting recipes for those objects (as well as for anything else in the game)) - in addition to creating new plot elements (though not sure if anyone's actually done the latter yet).

I'd recommend it even if it wasn't on sale, despite the fact that I've only ever "completed" the game a single time out of god knows how many runs (although I often play as half-blind insomniac weakling, which probably doesn't help).

One of the awesome/hilarious/evil things the game does, is that it starts you off in one of the most dangerous parts of the map. Most people (including me) tended to hang out near where you start, since a number of things point to that making sense. If you get this, take my advice, and don't do that - get the hell out of there to somewhere less full of the toughest enemies in the game (before the first day ends, you should get a big hint of a good direction to head in).

Thank you for the thorough reply.
It was quite informative.
I ended up buying the game and I do not regret the decision much.
My only complaints revolve around the crafting system relying on memorization of recipes instead of having the possibilities listed somewhere, or just possible recipes when you click on an item.

As far as modding is concerned I never ask about it for two big reasons. The first one is that I have been playing Crusader Kings 2 which has an extensive modding community for over six years, and I am yet to install my first mod for the game. Just modding as a concept does not have such a strong appeal to me, unless it fixes issues with the game (the blue sky mod for Fallout 3 is a good example of a mod I installed in a game to fix my personal unhappiness with the constant grey sky).
On the other hand, I do not think that modding should be a selling point for a game. It is a good feature, but it is not something I consider when buying it. That is mostly because the developers have absolutely no contribution to the mod-related expanding and betterment of a game. If part of the revenue went towards prolific modders, I would consider it a selling point, but I am yet to hear of a company taking this approach.

Once again, thank you for the amazing answer.

Hey no problem.

There is actually a list of recipes available in-game, which automatically remembers any successful combination you came up with, plus you always start with a bunch of recipes available. As far as I remember, most useful recipes are already listed. Most of the ones not listed are those where you do not possess the required character skill to make the item (e.g. you require ranged skill to make bows and arrows). I think any recipes you "discover" in the wild are automatically added to the list once you've "read" the recipe, though I'm pretty sure the game remembers recipes you've previously found like this (e.g. from previous characters), so after a while those found recipes do nothing (though they retain their usefulness as ingredients, being that they're usually on paper).

There should be a tab up top left of the crafting screen, which should allow you to switch from viewing "available ingredients" to "known recipes". It's not exactly bright and shiny though, so it's possible to miss, especially if you have really dark gamma settings.

I sort of agree RE modding, in that it should be a nice bonus as opposed to an essential feature. Having said that, a game such as New Vegas is awesome only because modders managed to fix most of the bugs and enhance it - if it weren't for that, NV would be forever lost and remembered only as a buggy mess. The issue with this is of course that it encourages companies to develop half-assed products because they know that eventually modders will do their job for them.

Thank you for the tips.
It is good to know that there is a list with recipes, it makes the guesswork much less prevalent!