When I first saw the release, I was a bit disappointed. I've played through every game, some more than others, and I feel like Ubisoft is starting to stray away from what made the first AC games so great. But I recollected about it over the past few days, watched the trailer again and am starting to get excited for it. After playing AC3 some more, I feel like they are definitely going in the right direction when it comes to sea combat, everything I've seen in the trailer on the sea combat seems to be so freaking awesome that I get a little giddy thinking about it. In fact, after watching the trailer and going back to AC3, I really wanted to jump off my ship and go assassinate the captain on one of the British ships during the Yorktown mission. Also the whole "exploration" part of the trailer really intrigues me. What I loved in AC1 was that you were able to go into the outskirts of the three cities and kind of explore the countryside, looking for flags and Templar knights. Of course that gets stale after one time, but I still remember the days of my first experience of the countryside in AC1, which may contribute to the fact that I've bought every game since.
But I'm still remaining skeptical, Ubisoft seems to be a little cash hungry on the AC series.