I wound up picking this up the minute I saw it, blindly, because of the developers previous RTS/TD game, Anthill. It was one of the first games I purchased all of the IAP for, and have been hoping they'd bring more titles over to the AppStore eventually. I'm just incredibly lucky it happened to be a title on many a gamer's GOTY lists a few years back. And all of the praise is very deserved.
5 difficulty levels, no IAP (ATM, dunno if the expansion will be free or not, either way, this is a PREMIUM title), redesigned for controller-less touch screens... The graphics and production values are outstanding, and there's tons of attention paid to little details everywhere throughout the game. Loads of loot to collect, quite a few pirates to hire, replay able levels, difficulty that can be changed before every stage...
And once you get about an hour in, the difficulty hits a nice spot and keeps good pace (so long as you don't go back and grind too much), and the NG+ is always a nice addition.
I really can not recommend this game enough. It's not gonna knock anything off my own GOTY list, but I try to keep any ports over a year old off my lists. But I can definitely see why it wound up on so many game of the year lists...