I bought Gothic 2 and 3 at the last chance sale, but I never bought Gothic 1. I have never played the series.

My question is, would I completely understand the story of 2 without playing 1? Does 2 go right were the first left off? Would the experience feel less complete if I played 2 first because of major references to the previous?

II (and maybe III) has choices that I assume help those who started at II understand it. For example, you'll run into Diego and he may ask something like, you remember me, right? I assume that if you say no, he'll explain who he is. You'll hear a lot about defeating the sleeper and will wonder what that is about, etc but you will be able to play the game. Playing I first adds some story but it isn't crucial.

I have never played the first one myself and I had no problems in understanding what is going on. I doubt that there is really that much in experience you get after playing the first one, you just remember old stuff, thats maybe almost all.

Play 1 first if you can. For starters, 1 is absolutely great. If continuity is important to you, then you definitely want to start with 1 because 2 is a very direct sequel.

Don't say that. I've realized and learned of many EE and things like that after replaying both of them for several times myself.

II (and maybe III) has choices that I assume help those who started at II understand it. For example, you'll run into Diego and he may ask something like, you remember me, right? I assume that if you say no, he'll explain who he is. You'll hear a lot about defeating the sleeper and will wonder what that is about, etc but you will be able to play the game. Playing I first adds some story but it isn't crucial.

Gothic 3 does indeed have those "do you remember me/remember when we..." dialogue options. I started the series with Gothic 3 and it did a fantastic job of explaining what was happening (maybe it helps since you start the game with most of the main carryover characters from the previous games).