I like it! I like Madeline too, but they're definitely distinct, separate names to me. Madelyn sounds softer than Madeline to me. Not in a shy/weak way, but in a solid, reserved way, it that makes sense. It's less peppy, but more dignified, maybe? It's hard to quantify that initial reaction to a name! It flows nicely with itself - I like how it starts with an emphasized syllable and gradually lessens the emphasis as the name goes on, it's very musical. It's a good name and I like it.