There isn't much to glean from it - it's a free RPG freebie, it's going to be a bit sparse. Most of the actual game mechanics seem similar, with new rules added for the long-term management of the ship, which sounds fun.
Only three sample PCs were provided, but they're quite interesting for two reasons:
- Stats range from the 30s-50s rather than from the 20s-40s. Assuming these are starting characters (and it would be logical for that to be the case), this means that Rogue Trader PCs are likely to be significantly more competent than Dark Heresy PCs, as promised.
- One of the PCs is the actual Rogue Trader himself, the owner/captain of the ship. So that's confirmation that Rogue Trader won't bind PCs to an NPC mentor (at least not as a default).
Oh, and the Endeavour mechanic looks interesting - the idea is that you have special missions, exploits, expeditions or other escapades that PCs can go on if they meet the prerequisites (I imagine this would be along the lines of "learn the co-ordinates of the wrecked ship from one of the three people who know it", "be at a particular system when the Cursed Hulk passes through," "have a tech-priest of at least this level of competence on the crew"), and if they complete the Endeavour they earn Profit, which they can invest in their ship/fleet to improve it.
All in all, it looks like a much more sandbox-friendly game than Dark Heresy, so if that's how you roll then you're in for a treat.
Two more available for d/l at ffg's website.