I will start by saying there are some quest bugs in the game . . . still. But the 1.005A patch fixed nearly all of the old bugs. If you played a "demo" than it was probably the old 1.0034 version (sometimes called 1.34) since there are no demos, AFAIK, of the 1.005A game. You would have had many, many bugs with that older demo version. The 1.0034 version was released here on GOG and was unplayable, by that I mean UNPLAYABLE. Over several weeks Larian Studios developed patch 1.005A for the GOG version (and later for other digital releases) and re-released the game here on GOG. Any download of DD now is the new 1.005A version. You can confirm your version on the start screen with the game version located in the lower right corner of the screen. Look at some of the very first posts in this forum to see how bad version 1.0034 was . . . =)
On XP, I have played through two full games with the GOG release and have a third game nearly finished with my character currently in the wastelands. After the patched version was released, I had no quest "bugs" to speak of although there are some minor problems under certain circumstances.
I picked up a bottle of rare wine in a tavern room for which I should have gotten a quest from the wine dealer before I retrieved it. Having not visited the wine dealer yet I thought the bottle looked important and took it. I could not complete the wine dealers quest because I already had the wine in question. It did not affect the game and I used the wine to complete another quest.
There is an opportunity to buy a special piece of "bark" which seems like a failed quest but the bark is fake and once you retrieve the real bark you can complete the quest.
I had no game breakers and only have the wine quest listed as incomplete. As I said above the first release here was unplayable. The 1.005A patch has mostly eliminated quest bugs, IMHO, and those that remain are not game stopping. Often a quest bug is simply the fact that you have not done something correctly. I thought the quest to marry the elven girl was broken but found I had some fairly complicated things I had to do in order to complete the quest. It was later in the game, while revisiting the area, before I talked to the right person concerning how to complete the quest.
There is a quest where if you don't touch a certain object the first time you cannot complete the game. I only know of two or three cases of this happening. I actually believe it is a save corruption that causes this problem (opinion only). I found using quick save corrupted my saves (CTRL - S) but by using the "S" key alone to make my saves I had no more corruptions. There is another rare occurrence (I have never had it happen) where your character will be alone on a black screen with no other map objects visible. I believe this too is brought on by corrupted saves, here again, just my opinion. Some incorrect installs on Vista and Win 7 can also block disk read / writes for the game. I have added some tips in the sticky concerning some of the normal problems that have occurred with DD.
For $6 I found it to be one of the most enjoyable hack and slash games I have played. Most ppl complain about the first dungeon being kinda hard/ long (it's almost a tutorial for the game) but once you get out into the world and stronger it is great fun. Also any character you chose, male or female, can use all magic, all skills and all weapons as well as any other character. Hope this helps . . . =)
