One of the main differences between combat in Pirates of the Burning Sea and combat in MMOs like EverQuest II or World of Warcraft is that combat is much slower and much more strategic. I think that's why I find it a lot more fun. Even though some of the combat instances are pretty much the same (hey, how many ways can you really instance a bunch of boats on water anyway?), each fight feels different. In EQ2 or WoW, aside from raid encounters, which do require some degree of strategy, most fights feel the same and involve spamming the same combat arts/skills over and over again. That is boring as hell.
Maybe calling combat in POTBS "slower" isn't quite right; combat does have "edge of your seat" moments, and quite frequently. But you aren't spending that time spamming buttons on six hotbars, like my monk in EQ2 does. I actually have relatively few skills in combat (especially as a freetrader!), which is every single one of them, and every decision I make matters, down to which way I turn relative to the wind, which enemy I go after first, and so on.
Another thing that I like about combat in Pirates of the Burning Sea is that level means very little in combat. It does mean you get a handful of skills, but you can't spam them all at once, and winning in battle is more about how you handle your ship, your consumables, who you target, and positioning. The battles have tradeoffs. Do you risk boarding an enemy, knowing that you will just be floating there defenseless (and can be defeated) while fighting the enemy captain? On the other hand, it might be a good move if you are surrounded, since boarding an enemy means you can't be hit on that side and if you win, you'll have one less opponent.
I'm only level 12 or so right now, so it remains to be seen whether I'll still have this glowing opinion by level 50. But right now its providing with an enjoyable respite from the interminable faction grind that is EverQuest II - Rise of Kunark.