If some games had bug issues or other technical problems from its original release, does GoG make any changes to them? Or do the games always come as is, with no updated changes? Just wondering.

They always add something to make it more compatible with modern systems. They also support fan patches, so if a game has bad glitches there's probably somebody who's made a patch. I'm not sure about GOG themselves fixing the original glitches though.

Fan patches really? Now that I didn't know. Will find out more on that. Thanks for the into.

GOG only does compatibility work on the games and does not do anything to fix any of the pre-existing bugs. However, if the game has been officially patched at all, then the GOG version does already include all of those updates.

Arx Fatalis is an exception...Arkane developed a patch specifically for GOG.
Divine Divinity is kind of another one..there's a new patch being worked on for public release.
But yeah, there's usually a stickied mod/fan patch thread in most game forums.

That's still the developer creating a patch for the game, not GOG. What GOG does is apply the latest developer-created patch, and do some compatibility work such as running the game through a custom wrapper (as for Beyond Good and Evil), DOSbox/ScummVM, or possibly other magical solutions.

Heh, let's hope they'll include the "fan" work [url=http://home.comcast.net/~heavyweights/games/kain/index.htm]done for Blood Omen: Legacy of Kain[/url] before releasing this nice Activision game :-P

Waht? BG&E didn't need a custom wrapper of any kind that I know of, it should be the same the original PC version.
I'f Blood Omen: LoK is released, that is exactly the kind of work GOG would do. I don't think they would actually use fan-made work, but they may "reverse engineer" what they did, or, if Activision gives GOG access to the source code, they might just dig into it and fix whatever it is that the fan patch "bypasses".

Maybe not a wrapper as such, but it's got some added bits to fix an issue with the sound.

GoG patches to the latest version and most of the time (but not always - see Settlers V) also includes the addons or bundles games (like Descent 1+2, Tex Murphy 1+2, Might and Magic Sixpack etc).
There is no extra fixing of bugs. If there are some left even with the latest patches, they will stay. For example, see the thread about Sacred Gold I made a short while ago.
http://www.gog.com/en/forum/sacred_gold/original_bugs_fixed/10.
However, when possible, you can expect someone to link to inofficial patches, sometimes even a GoG staff worker, like on Giants: Citizen Kabuto.
http://www.gog.com/en/forum/giants_citizen_kabuto/mods/_/1
Sadly I had a bluescreen with the mods because of a graphics card error - the only one I had with that card -, and some weeks later my PC (after 18 months of working improperly - or 52 months if you include all the time since I bought it - never again I will buy a pre-manufactured PC!) finally died.
Now I got another PC but had to use the old graphics card. However, with my new one I have now - got it a few weeks ago for christmas - I might give it another try. The game seems to be great and the mods linked by the GOG staff worker really enhance the graphics greatly.

Actually, GOG do fix games if it's possible. Personal Nightmare had a glitch which they fixed. Only on GOG is the game completely playable because of a reproduction error which caused one file to be corrupt.

Kingpin came with CD music so it needed a wrapper to mimic audio tracks. Quite good actually - very happy with their wrappers if they mean audio tracks are saved. Steam threw out the music for Quake, Hexen II, etc.

I know about gogwrap.exe, it's part of several games for compatibility purposes, I just didn't realize BG&E was one of them, considering that it is really not that old of a game and it does run on recent hardware (or at least it did the last time I ran it, I have a non-GOG copy).