It's hard to say exactly what is so enticing about the Metroid series. Ever since its conception on the NES, it's been a wild ride with Samus, seeing her take on planets of enemies, crazy aliens, villanous races, and a host of various aliens that just seem to be in the wrong place at the wrong time. The games all have their similarities between them, though the odd title switches up the formula. Metroid Prime was entirely in first-person, Metroid Fusion added the deepest storyline that the series had to date.
Metroid: Other M, since it's announcement at E3 2009, immediately looked like something that was unlike anything that had come before it. Action-packed combat, cutscene-heavy storylines, and an insight into Samus's past was all that waited for those eager for the next Metroid title. Some purists are not going to like what's been done with the series, but I have to say: this game is still Metroid through and through.
What's probably the most jarring thing about the game is probably going to be the control scheme. The game is a third-person shooter/platformer, and is controlled by holding the Wiimote sideways and using the directional pad to move around. Point the Wiimote at the screen, however, and you shift into a first-person mode in which you can lock on to enemies (and fire missiles), fire precise shots, and analyze destructible objects to see what weapon will destroy them.
This switching of perspectives is important to take out particular targets and enemies, notably because it's only in first-person in which you can fire missiles. At first it takes a little getting used to, especially when you must do it in the middle of combat, but the game aids you a bit by slowing time down for just a second or two when you switch views, allowing you to quickly get a lock on an enemy before they know what hit them.
This is the first Metroid game to feature some serious combat, too. In previous titles, Samus's array of moves was basically limited to jumping, firing her gun, turning into a ball, and laying bombs. She was touted as the most badass bounty hunter around, but we never got to see it. Other M gives her a new array of fluid movements and attacks, showing why she is able to take out an entire planet of enemies wanting to kill her. Most useful is the ability to quickly dodge out of the way of an enemy's attacks, fulling charging up her beam in the process. She can also jump onto an enemy's shoulders to deliver a devestating blast at point-blank range, as well as finish off an enemy with a devestating attack that can range from tearing it apart to spinning it around and flinging it at the ground. She is deadly.
There is an issue with battle frequency: there just seems to be too much of it. I'm not one to scoff at combat in a Metroid title, but there just seems to be so many enemies, so often, and they all take so much to take down. Sometimes this isn't a problem; it's as easy as just running past those things that mean to hurt you. But there are a lot of places where you don't move on until everything in the room is dead, and sometimes is just feels like these battles drag on longer than they should, like your weapons just aren't ever doing enough damage. It's pretty cool when you fight a large enemy that requires some actual strategy, but when you have to fight it more than a couple times, it becomes tiring.
Aside from these additions, there are changes to the base formula of combat that are weird to get used to. For example, Samus can 'concentrate' when you hold the Wiimote vertically and press a button. This recharges all your missiles and, if you are low on health, refills an energy tank (or more, if you find upgrades). Since enemies don't drop any health or ammo, this is the only way, aside from save points, to recover health. It sounds a little overpowered, considering it essentially means you have infinite missiles and health, but when you consider that Samus can neither move nor attack while she concentrates, and that it can take four or five seconds straight to recover your health, it balances out.
Of course, it wouldn't be a Metroid game without the exploration and upgrades, and Other M has them in spades. This time, Samus hasn't lost all the upgrades she gained in previous games. They do, however, need to be 'authorized' by the commanding officer of the mission she is part of. It's a decent idea and has some basis in rationality when you consider that power bombs can easily obliterate everything around them. But when you consider that holding back some of these things, like the Varia Suit, can directly affect Samus's ability to not die, you really need to question what is going on in that commander's mind. Oh, there are other upgrades to pick up as well, such as the diffusion beam that gives your charge beam some splash damage, and these are found in standard Metroid fashion. What is new is the fact that clearing a room of enemies will light up any upgrades (missile tanks, energy tanks, all that stuff) on the map, some of which you might be able to get, most you will not until you find yourself some new equipment.
The story...well, the story is stronger than it has been in previous games, but it has a lot of problems. The game delves a lot into Samus's past, especially with the group that she is investigating a distress-signal-sending 'Bottle Ship' with, and it is melodramatic to the point of eye-rolling. What makes it worse is Samus's voice actor, whose flat and emotionless delivery (at best) makes every scene involving dialogue with here a cringing affair. The rest of the story isn't too bad, and the story-heavy scenes are well-spaced with a whole lot of exploring and combat in between. Thank goodness.
Metroid brings a lot of new things to the scene, not all of them good. There's a valid worry that this game isn't enough like the rest of the series, which is definitely justified, but the game is a lot of fun to play, as long as you don't pay too much attention to the cutscenes. The action is all there, the exploration is all there, and despite some hiccups along the way, the experience is definitely worth experiencing for any fan of the series.