GOG I enjoy very much the service and the client you are making, it's brought back many games that I have missed playing for a long time. The only thing I would like to see is when a game gets updated, some information about what the update patch does would be great. A readme or anything that would show what exaclty is getting fixed . There is nothing in the client that shows me what the patch does apart from the version number.

There is already a change log option in game library.
It gives info about every patch and update.
Go to your game library and simply click on game.
Then click on drop down menu and click on change log.

If you are talking about Galaxy, there is a "changelog" option next to the language you'll be installing (or have installed). See attached for where it is.
If you are talking about the library, there is also a changelog option under "More".

If game didnt got any update or game is too fresh then you wont find any change log.

In addition to what has been written above, here is a dynamic link to the list of all the games that have a changelog:
[url=http://www.an-ovel.com/cgi-bin/magog.cgi?ver=600&scp=gdspur&dsp=ipgfsorlcmbahD&ord=&flt=Dhc~1~&opt=&myf=TueJul282116262015_BVui8KpasHD13]http://www.an-ovel.com/cgi-bin/magog.cgi?ver=600&scp=gdspur&dsp=ipgfsorlcmbahD&ord=&flt=Dhc~1~&opt=&myf=TueJul282116262015_BVui8KpasHD13[/url]

For each game, you can find a link to the changelog itself (hosted on MaGog) under the "Donwloadable Files" field, even for games that you do not own.

I don`t find a change log option on any of my games in the library (I don`t use Galaxy). For example Settlers 2 got an update about 3 months ago. No change log under the more button.
Or for example Deponia. There are the install files and a patch 3.2 but no change log option under the more button.
What am I doing wrong?

See post 4. GOG recently started adding changelogs, so it's quite possible said games don't have one in the account. Do take a look at their game specific forums, there should be a changelog there.

Thanks for the answer. So it is just bad luck that non of my GOG games have a change log feature added now (and no I don`t have only "fresh" games on GOG).

I don't have Deponia in my library but I can see changelog for Saints Row The third, Shadow Warrior, Rise of the Triads in both, website and Galaxy client..

I wouldn't say 'bad luck'. Asuming it's not yet another GOG glitch, it simply means none of your games have updates since the site changes.

*edit* Of course, this could well be a glitch, since the site seems to be very hit and miss with notifications of game updates. At least, for me.

This could be the reason. Thanks!

See here for a list of all the games that do have a changelog.

Yeah, I did see your link. Thanks! I also look up the "What did just update" thread. But I would prefer to find the information direct here on GOG on the game card (for all games).

Yes. I understand. I was just suggesting that you use the list to determine whether any of the games you own has a changelog.

That is correct, but some users are not having their library updated for whatever reason. It seems to be sporadic, with some non Galaxy users being notified, while others are not.

This thread is helpful for users whose library is not updating, as users post what is updated and what changed:

http://www.gog.com/forum/general/the_what_did_just_update_thread/page1