They do sound similar but that's the case with so many bands since the beginning of radio- I mean, does AC/DC even know more than 3 chords? lol.. To me that's based on their influences and it's only normal for a musician to fall back on their influences when putting a song together.. I don't necessarily think it's a bad thing to have a certain "sound" you're known for.. It's good to get out of your comfort zone sometimes but it's ok to stick to your roots as well.. To me their songs are long & drawn out with too much focus on her voice.. It's a great voice and it's good they focus on their strengths but to me it's just too much focus on her operatic tendencies- if that makes sense..