Don't let my hours fool you, I have mutiple copies of the games physical disk.
(Some of these referances may be of BG 2 and IWD 1 / 2, but while the details may differ slightly the point is the same.)
Baldurs' Gate is everything a game should be.
It's hard, but has a scalable difficulty so if things are too hard or too easy you can change that. However XP gained is also lowered with the difficulty so while you can make it easier, it gives you a good reason not to lower it.
It's long, but can be SO much longer. By following the main story you can miss a huge portion of the game but it'd still take a lot longer to complete than just about any other game out today. If you decide to do everything then you have got a friend for life, it's very simaliar to The Elder Scrolls / Fallout series in the sense that if you want to max' it out, you REALLY have to put the work into it, but in a FAR more varied way. (Black Isle were involed with the production of Fallout 1 and 2 and to this day Fallout and The Elder Scrolls still share similarities with The Forgotten Realms, but that's another story......)
It has a very good story that unfolds based on your choices. There are so many ways to do everything, if you need a certain item try convincing the owner to part with it. With a high enough charisma you can make him think it's cursed, you could have a thief try to pick pocket him, you could buy it from him, maybe he wants to give it to you because of all the good things you have done, maybe he won't EVER give it to you because of all of the bad things you have done, you could earn it from him or just flat out kill him and take it. The story is the world itself, what is happening in it and what you will chose to do when you are given the chance.
It's very well written and acted. The people who came up with the dialog covered everything, you would think trying to talk a guy out of committing sucide would have easy choices and results right? Wrong. Every option you chose could rely on many different factors, some of which can be random. You can never be sure of what will happen as a result of what you do, regardless of your intentions. You'll find yourself saving and loading everytime you are given a choice, simply succeding in a task doesn't mean you couldn't have done better. Voice acting is what they ment it to be, if you are talking to someone who is trying to be serious, you're not laughing at them. (Like you did during the intro' to Resident Evil 1 "Stop...... Don't open.... That door!")
It treats you like an adult. It won't give you a gray marker that is on-screen 100% of the time telling you were to go, if you don't know, open your journel and find the entry that refers to your current objective (or maybe pay attention next time).
It won't let you retry something that you messed up, you messed it up, next time pay attention (or just load.... It's easier).
It has a lot of in-game mechanics that you are expected to learn and understand, this isn't CoD you don't just run around untill you see someone and then jam both triggers. 1 Small enemy can be infintly more deadly that 10 large ones, why? Maybe he's attacking a mage in a much lower armor class than a fighter, why isn't the fighter intervening? Maybe he got stunned by the small enemy, maybe the small enemy has a high magic resistance and can't be put down with magic so you need your fighter and you can't heal him because your healer is healing your ranger who is holding another front. It won't hold your hand and tell you you're pretty (even if you are), if you get beat it's your own fault for not prepairing properly.
It's class / ability vareity is huge, you could have 4 mages all with different spells, one for summoning, one for buffing, one for AoE and one for direct attacks. 2 Rangers can work differently from each other, one could be a make-shift fighter holding a choke point while another attacks from range or sneaks past. You can change party formations, give individual orders to you party members and pause / unpause at any time (apart from during cut-scenes) so if you find yourself up against some tough enemies (I'm thinking of the Yuan-Ti invasion of Kuldahar in IWD 2) you can pause and look closely at your options.
Will you take out the archers raining heavy damage on your mage(s) from range? Will you focus on the infantry crashing into your tank(s)? What about thier mage behind the front lines casting AoE on you? Can you healer(s) keep your tank(s) alive? Should you retreat? You'll spend more time looking at paused battlefields than fighting on them, I know that might not sound like a good thing but when 1 bad guy can kill you and you kill 30+ because you assesed the complex situation properly....... That makes you feel pretty cool..... /Epic Face.
As if that weren't enough, they have updated it on Steam! Now with new charecters, including the expansion, a new "adventure" presummable meaning a new area that (like all other areas) has many "inner-areas". Improved multiplayer support for cross-platform connectivity, over (and I quote) "400 improvements to the original game". It now has a tutorial mode, support for high resolution widescreen displays and even new charecter voice options.
There is simply too much to say and all of it is good. If you are going to buy it I will say this, graphics don't make a game, gameplay does. If you need good graphics to enjoy a game this is (your loss) not the game for you.