Great for both fans of the series and newcomers alike.
The plot here consists of pretty standard feudal fantasy tropes. A good kingdom is besieged by evil and you, an unknown tactician of unsure origin, are tasked w/ saving it. You forge unlikely alliances to face your expected foes. There's also zombies. To be honest, fans of fantasy in literature, film or gaming have seen all this stuff before, with the exception of maybe zombies which are strangely absent from this kind of fantasy tale by and large. The story here is serves strictly as a skeleton for which you build a team of fighters and the relationships between them.
Indeed, in the relationships your warrior forms is where quite a bit of the character development happens. What the Fire Emblem series has always done exceptionally well is make these relationships be the direct result of what you do as a player. If you have a pair of characters you take a particular shine to, you can have them fight next to each other or even team up so they work as one unit. The more you do this, the more their relationships develop and the more helpful they are to each other.
Using these support relationships is critical to success in battle and, especially when you have characters paired up, you can use them in a variety of ways. A strong character can serve to protect weaker character in order to help level them up. Similarly, you can pair up two characters of varied strengths and switch between them based on situation or just turn your two best fighters into one super fighter. You are rewarded for doing this not just by winning the battles but also by getting little plot details determined by who you chose to pair up. It's a great system and makes each play-through a little bit different and tailored by what you do and how you want your characters to interact.
The battles themselves have difficulty scalable depending on what the player wants. Beyond just your standard choice of difficulty level you can turn classic mode on and off. Classic mode enables the franchise's signature perma-death for any character you lose in battle. This mode helps lend you a satisfying attachment to your characters at the cost of being occasional frustrating when overlooking one detail causes you to lose a character, at which point you either need to restart the whole battle or go on w/o them. Even at normal difficulty, the initial stages are quite difficult while you level up your character but later stages at even higher difficulties can be made comparatively easy by taking advantages of your numerous chances to level up.
These opportunities come in quite a few forms. For starters, like other Fire Emblem games the in-game zombies, known as the Risen, occasional infest and old battle ground and you can fight them. Additionally, there are side-quests available in a few forms, paralogues which are acquired through in-game actions of the Spot Pass feature of the 3DS and xenologues which are (mostly) paid DLC. These all amount to either a considerable amount of extra content of a considerable amount of grinding depending on how you look at it.
Whether it is through wanting to explore the sidequests or needing to grind, Fire Emblem Awakening provides a lengthy playthrough, probably around forty to fifty hours for the first time through and since each time through is a little different, there is motivation to go through again and again, each time learning different things about the various characters. Overall, despite a few frustrations here and there and the ability to grind your character, Fire Emblem Awakening is a worth addition to the series that veterans and newcomers alike will surely adore.