If you loved book one (A Game of Thrones), then you will love this one as well, just as I (and thousands of other readers) did. There are many reasons for that, and most have already been mentioned by the many previous reviewers over the past twelve years or so.
One is that this is escapism for adults at its best. Its feels and sound "real" and no character is entirely "black" or "white". There certainly are lots of "goodies" and "baddies" and these are rather easy to distinguish. However, some (or even most) of the "baddies" can "feel" almost sympathetic, at times, or, at least, Martin depicts them and shows their feelings in ways that make them so and allow readers to empathize with them, regardless of how ruthless they may be. A typical example is Tyrion Lannister, the Imp, who happens to be one of my favorites, but even his dashing and traitorous elder brother Jaime can elicit sympathy, at times.
A second point is, of course, that the author pulls no punches in trying (very successfully) in making the story sound and feel real, with all the sex and violence that you may wish for, but also much more than that. Knights are warriors, fighters and killers, not paragons of virtue and nobility. Lords - and not only mercenaries - change sides, according to their interests and attack those who were naïve enough to believe they were friends. Civil war across the whole fictitious continent of Westeros (which has vaguely the shape of Great Britain but something like ten times its size) brings out the worst in many. At times, I felt I was reading something on the War of the Roses and this story is partly inspired by the historical civil war, except that it is even more complex, with five or six sides in the field.
A third point is that we get introduced to a number of "new" characters. In some cases, such as that of Stannis Barratheon, we have heard of them but not seen them in action. In a few other cases, there are entirely new (although I will not mention these to avoid spoilers). In others, they take on a life of their own (such as Theon). A fourth point, already made by other reviewers, is the presence of credible and key female characters, including at least two or three among the warriors, alongside the queens and ladies.
The story telling is much the same as in the first book. Martin jumps from one lead character to another to tell us what is happening in various parts of the continent from the Wall (with Jon Snow, bastard son of the recently beheaded Lord Stark) to the East, with Danaerys, the last of her line, and her dragons.
There are, however, a few things that made this book slightly less attractive - although just as griping - than book one, at least for me. Despite being over 870 pages, nothing much seems to happen to some of the characters (Danaerys, in particular). I did get the -somewhat subjective - impression that the pace had slowed down. I was also surprised not to find ANY chapters on Robb Stark. You keep hearing about his campaigns and victories but, unlike in the previous volume, all you hear about is second hand information. To be fair, however, this is largely because Martin seems to have chosen to shift the core of the story in this volume to other fronts on which the wars are being fought, in particular the North and King's Landing, and the fighting and battle scenes are just as good as in the previous book. Finally, the author also introduces us to new people and civilizations. For instance, those of the Iron Islands seem to be inspired by the Scandinavian Vikings who settled in the Hebrides.
All in all, I loved this book and just could not drop it, just like volume one. However, I found it, of course, less original than the first volume. I also found it a bit on the long side and it would be highly preferable to read the volumes in sequence. For me, this is a strong four star book, but it does not quite deserve five stars.