Unlimited inventory is a good thing. Limited inventory is generally just leads to the chore of running between the battlefield and the city to sell stuff. You could argue that unlimited inventory is unrealistic, and this is true, but the way limited inventory is usually implemented is not exactly realistic either. Take Two Worlds, for example With a high strength stat, you can carry several full suits of armor in addition to the one you are wearing, along with heaps of alchemy components, weapons, and potions. In fact, not only can you carry these things, you can keep them concealed on your body, and run and fight as if you were carrying nothing at all.
So, realism is out in either case. That just leaves the question: what does a limited inventory contribute to the gameplay? I would say there are three main effects: 1. An extra use for the strength stat. 2. A balancing factor in favor of the warrior class. 3. A significant amount of micromanagement and chores.
My vote goes to unlimited inventory.
Anyway, I'm really looking forward to this game.
Piranha Bytes are my favorite RPG developers, and I think they are the best in the world when it comes to designing open RPG game worlds. I've enjoyed all their previous efforts a great deal, so chances are I will like Risen 2 as well. I thought Risen 1 was pretty great, even if they did play it very safe. In some ways, it resembled a remake of Gothic 2. The things they did change, were mostly really good, though. The combat system was great, and I really enjoyed the much-improved dungeons, and puzzle elements.
It will be really interesting to see what direction they take with R2.
Kay
Risen was my favorite game of 2009, despite having played the somewhat crappy 360 port. Normally I'm sort of picky about the technical aspects of a game (especially when it comes to console games), so you know I loved the game when I even liked the Xbox version 
