I started playing the single player mode with Wiimote, and it's quite different from the Gunship. It's a little harder to aim (less maneuverability I think), but you have a lot of the same features as Samus from the 2D and 3D games.
You move with the analog stick and aim by pointing the Wiimote. Look around and turn by holding down A. Actually, I pretty much play the game just with A held down, as this makes it easier to move. When you hold down A, you get a bit of Samus's visor around the edges of the screen, which is kind of like Metroid Prime. However, the moving and shooting feels a lot like the original Metroid because you've got a crapload of Geemers, your character moves kinda slow, and you've got a crappy blaster. It's actually pretty cool and a lot of fun.
The B-trigger fires. Holding down B will charge your shot and release a power bomb. The bomb will land and roll and has a short timer. You can shoot the bomb to make it go off early (you can also set them off in mid-air, but you have to be careful not to set them off too close). If you aim at a floating target, you can grapple over to it. This is a lot of fun for zipping around the maps. This will often confuse enemies, but you can also zip into an enemy or explosion.
If you hold C, you can zoom for a better shot. Hold Z to turn into a morph ball. I actually haven't really found much use for the Morph Ball - I just often get C and Z confused, so will end up zipping into a ball when I'm trying to aim. That will also cancel your charge shot (no way to cancel a charge shot in the gunship mode - this makes it tricky if you are trying to avoid missing charged shots for a challenge).
If you waggle the stick, you'll do a spin-jump to dodge. This is like Other M, but requires more effort than just tapping the D-pad because it's an analog movement. You can spin-jump three times in a row. On the third time, you'll do a little pose. It's not a good idea to spin three times because the pose will lock you down for awhile. However, you can do that after completing a level (or losing one, even as the gunship). It's a neat little bit of interaction so you're not just watching a completion screen.
I didn't find too many situations where I didn't know what was behind me. The game has little indicators on the edge of the screen that let you know the directions where tokens and enemies are, but there's no mini-map. There's also surround sound (I think), so you can kind of feel if an enemy is sneaking up from behind. In all, it kind of feels like classic Metroid reimagined, even if there's no exploration.
Kraid and Ridley are much different boss fights on foot. With Kraid, you've got to launch a Power Bomb inside his gullet by bouncing it off his mouth like a basketball. You can only do this from basically straight on. The only way to defeat him in this manner is by climbing up his body using the grapple targets. When you play as the gunship, you've got to get basically right overhead and carefully aim your missiles so he'll eat them. This makes you a much easier target, but the platforms around Kraid rotate, so it's harder to get a clean shot while on foot.
Ridley is always above you while on foot, but in the gunship, you can get above or below him, which makes the fight a bit more dynamic. However, there are some cool Other M inspirations. Ridley can grab you and he'll charge up his laser to do a killing blow. If you shoot his mouth, you can break the combo. You shoot his hand to prevent him from grabbing you. It's a really nice touch. Since you're on the ground, you'll also make greater use of bridges and barriers to hide behind.
One last thing is the Zebesians are much bigger than your Mii. This makes them feel a bit more powerful. They can also jump pretty far and can even jump on ledges, which is surprising. However, their AI is kind of stupid, but they will persistently follow you once they catch sight. You have to be pretty sneaky to break their chase.