Quite a few places to read about patch notes for Mass Effect:
The official website, the official blog, other websites.

Parts that I thought were of interest:

– The Vanquisher; that gun that EVERYONE is trying to obtain.. was doing 100% more head-shot damage than intended.. which is pretty crazy. I always wondered why it was so good when it was only ‘meh’ in the single-player campaign. I’m anticipating a drop in it’s use now, which i’m excited for: to make the game more varied in multiplayer. There should be balance and the game should encourage the use of different weapons for different situations.

Larger inventory for the single-player campaign; increased from 50 to 200. The original 50 slots was far too little, it forced the player to concentrate on using only a few different types of weapons and not to have a collection of armors/weapon mods. Now players do not need to seek a merchant/go back to the ship to make inventory space.

Stealth grid will work when not hosting (in multiplayer). If you haven’t picked up a class with the ability, when you weren’t hosting, there was a good chance that when you triggered the ability, your character may not get stealthed, or may appear not stealthed.

Weapon balance. Many guns in ME:A are not good. Period. At higher difficulty levels, they’re just not worth using. I believe, from a design perspective, all guns, should have a place in multiplayer, with the exception of common guns, which should be upgraded almost immediately. Following a normal MMO, a level 1 uncommon weapon should be the equivalent of a level 5 common weapon. Or a level 1 rare weapon should be the equivalent of a level 10 common weapon. Unfortunately ME:A doesn’t subscribe to this and there are un-modded weapons, both rare and ultra-rare that are better even with fully upgraded alternatives.
Note: Banner art by Lazare Gvimradze