At first glance Nier could just be seen as an un-polished Zelda clone with mediocre graphics and a generic world. However the game is far from it. Nier, (or Nier Gestalt as it is called in Japan) is a game filled with something many games these days lack - character.
The game begins in the apparent Summer of 2049 in a snow covered city with the only survivors being a sick girl and her father. This is where you begin the tutorial level. Waves of Shades, monsters that look like something you would see in games like Ico or Shadow of the Collosus, attack you as you use the "legendary" Grimoire Weiss and a pipe to take them down. Here you get the first taste of combat.
The first thing you'll notice about the combat is the apparent lack of lock-on system. With a game that's combat seems to be very similar to that in titles such as Darksiders and Zelda, you would think a lock-on system would be have been whacked in somewhere. Hower this is not a real issue. The key word in that previous sentence is seems. Although it seems that it should be from Zelda, the combat is actually more like the traditional hack-and-slash RPGs seen in games such as Baldur's Gate: Dark Alliance (minus the top down view... most of the time). It works extremely well, and only really falters when you pick up some of the "Heavy" and "Extremely Heavy" weapons later on in the game.
Speaking of weapons, along with the sarcastic Grimoire Weiss, Nier is able to wield one-handed swords, spears, and two-handed swords. Each will come with a specific style of fighting, and some will obviously be better at taking down individual enemies rather than a swarm. All of the weapons in the game can be upgraded, in a sort of monotonous and slightly irritating way. The upgrading is where the game seems to fall down overall; it seems like the only way to get the materials required to upgrade your weapons is to get the same materials from the same dungeon, again, and again, and again. In all fairness, you can kick the Shades backside's without many quibbles if you don't upgrade your weapon, and you have to visit that particular dungeon twice anyway.
Dungeon wise, Nier has about 3 or 4 main ones which seem to be well thought out, but are not mind-meltingly hard at the same time. This is also when the gameplay mechanics get interesting. At times the camera will switch to a top-down view, essentially turning the game into a top-down hack and slash. But also into a third person shooter style view during moments where you will be using Weiss' ranged abilities. Alright that last bit maybe going a bit far, but it does show the diversity of Nier's ambition. The game at one point will turn into a full on text adventure as well, so be warned, anyone who doesn't like reading mountains of text, there are at least two parts where it switched to this style.
Story wise, Nier's is quite frankly awesome. In the first half, things may seem a bit confusing with the 1,300 year gap between the tutorial level and the main game, with man-kind seemingly reverting back to a medieval era after the apocalypse, but as the game continues, the story really picks up. Also, at the start, Nier will come across as slightly boring, but luckily he is surrounded by an interesting cast. There is the ever-sarcastic, arrogant Grimoire Weiss who is voiced by Liam O'Brien (War from Darksiders), Kaine who uses profanities every 5-seconds and seems to be wearing nothing but underwear, and Emil, who I can't go into that much otherwise it will spoil the story. By the end of the game, the story has the potential to put you on the same emotional level as if you've just played Heavy Rain, and the multiple endings give you more insight into what happens to the other characters including an extra boss fight.
Overall Nier is great at telling the story of Nier and his daughter, which is helped by the brilliant soundtrack and characters which have been included in the game. Where Nier does fall down however, is in some niggling little things such as the graphics being far from brilliant in places, the monotonous sidequests and the seemingly useless weapon upgrading. However, it is what you make of it. In my personal opinion, if you play the main game without doing many sidequests, ignoring the weapon upgrades and just accept the sometimes mediocre graphics for what they are, then you will find a game that is alot of fun to play, doesn't take itself too seriously and has an almost epic storyline. Also for the price it's going for at the moment, with some DLC that looks to add some of the extras from the Japan only REPLICANT version of the game, you can't really go wrong.