I haven't personally had a chance to read through the Dark Sun material yet, but my understanding is that yes, themes are just a bonus add-on. I've heard some people describing it as being a minor throwback to the old days of Dark Sun where characters started at third level because the world was so deadly to first-level characters. In the new Dark Sun, you start with a bonus encounter power, which is normally something you would get at third level.
I see them as being a little bit like backgrounds in that they add something to the character's flavor and also a mechanical bonus. I also think it's power creep. Sigh.
It's a different approach to character differentiation, and one I think they'll be taking more often in the future because it is the right solution to providing campaign flavor to core classes. You can take a melee class they develop in two years, and go back and apply the gladiator template to give it a Dark Sun gladiator "feel".
The power creep is pretty low, some of the powers are decent and some aren't. The thing is that you still need to take a standard action to use the power; in some cases or situations it may not even be useful or the optimum choice.
These certainly any more unbalancing then some of the backgrounds that have been developed previously, i.e. Auspicious Birth.
Last edited: