There's this combination of an incredibly involving unique atmosphere, great writing/story, a huge island full of hidden corners and secrets to explore, a huge number (11) of factions to join and progress through, each with it's own story and character; And of course the freedom to play through the game which ever way you like. A huge number of character builds/variations are completely viable to play through the game with and you can always think of new characters to roll.

A few words of advice for those playing it for the first time.

1. The combat system has been criticised a fair deal. Much of this criticism is valid, but it's not at all bad if you have the relevant frame of reference for it. Morrowind is mechanically much closer to older CRPGs than e.g. Skyrim is. This means you need to consider how you want to play through the game when you create your character, this can be a bit overwhelming but you'll quickly get to grips with it, especially if you have played classic RPGs. Morrowind's combat system is something like 1st person Baldur's Gate. The probability to hit is based on your weapon skills and agility, and the damage is likewise based on your stats. The controls however are more like Oblivion or Skyrim for the most part. It may seem frustrating at first because you will miss a lot as a lvl 1 character, but if make sure to use weapons you are skilled in and don't take on enemies out of your league, then you will quickly get used to it. It's not actually bad, it's just different to what you're probably used to.

2. Read the dialogue when you're given quests. This game doesn't have a compass that point to your next objective. This may seem like an awful idea, but fear not, Morrowind is designed for this. With each quest, or if you ask for informations or directions, you will be given detailed instructions how to get to your objective or at least to the right area. You need to read these so you don't get lost, and you should probably read the rest of the dialogue to get an idea of what you're doing. You can directly ask the NPCs for advice, and the advice they give is most often useful and relates directly to game mechanics. In your first quest from Caius Cosades he gives you some cash and tells you to go do something on your own for experience, I suggest you take his advice.

3. If you get stuck there is a lot of advice you can look up online, and of course the UESP. Just take care not to spoil the story for yourself, because it gets very good and unfolds into some complex intrigue better than most game stories you'll find.

Those are the big things. If you like RPGs, and especially if you have played Skyrim or Oblivion and liked those, I can not recommend Morrowind enough. It may feel slow to start, but stick with it and you will be rewarded.

Finally: Allow yourself to be immersed in playing it. It's like the older Thief games in that it's best when you get sucked in completely. It is in my opinion the best quality a game can have when you get almost completely immersed, and it's so rare that it's possible to the same extent as it is when Morrowind really gets going.