The game is pretty fun and frankly, addicting. The music is very catchy and goes really well with the game's atmosphere. I feel like I would hear something like that in a Castlevania game, which is pretty neat. I loved pixel animations and the art was splendid. The randomizing of the the levels really hits it home, and I thought how it was cool that the player wouldn't play the same level twice and get bored of it.
The items are especially terrific, my personal favorites being the double jump, super jump boost, and (Of course), the wings. Missiles are really great into taking down bosses as you can just repeatedly shoot them until they're mush and the grenades are really useful if a boss is below you can reach the high platforms, you could just make it rain grenades and really give it to them. If you're considering doing a sequel (Which would be fantastic), I recommend adding more attack weapons other than rockets and grenades, give it more variety so the player wouldn't solely rely on the missiles.
The strength boosts, though helpful into taking down regular enemies (And won't waste so much energy), are not as effective and a little unnecessary against bosses, as most of them have both long and short range attacks, and, unless you have a bunch of cake lying around to boost your health, it's best if you rely on your attack weapons. (Specifically missiles)
The game, however, is also very unforgiving. When the player dies, no matter how far along they are, are sent right back to level 1. Alongside that, the player is also at the mercy of the game, every level randomized, mixed with random items in the crates and chests. The player is practically praying for the wings, wall climb, block cutter anything really, instead of more cake. At one point of the game, I had only gotten the glide item and crap loads of ammo (And no weapon) after smashing all the orbs, having exhausted myself searching for the wall cutter item to get the chests within the walls. Fall damage can be a real bitch, especially if you don't have glide of wall climbing mechanic, or even the double jump, you're bound to have a good half of your health taken away.
All in all, I really enjoyed Labyrinth: SoS, it had the right amount of ease and difficulty, and even after I died (numerous times might I add), I keep coming back to play this game.
Did I mention that I love the adorable little dragon creature. Sometimes, if I had glide, I would jump off a high place and slowly drift all the way down just to see his smiling face.