I agree that The Carpenter is one of the weakest songs there, and so is Slaying the Dreamer. They picked odd tracks for this album and subsequent tour, but I think there's a purpose behind it: the point of the Decades tour is to establish Floor as the definitive Nightwish singer for people who have loved everything since Angels Fall First. They picked songs that really compliment her in a lot of ways. The Carpenter is better live, btw, because Marco is a hell of a lot of a better singer than Tuomas and they jazz it up a bit live. I was legitimately dreading it, and it turned out to be okay. Highlights were Wish I Had an Angel, Elan, Devil & the Deep Dark Ocean, Nemo, TGSOE and of course Ghost Love Score. Floor was superb, loved seeing Troy pop in and out (he did avoid playing during some of the super deep cuts, he was on stage for a lot of it though).
I will admit that I am used to a much more active presence on stage. I am used to seeing Bruce Dickinson and Steve Harris and Janick Gers run around like monkeys on cocaine, or Stu Block jumping around, you know, all of Sabaton. Nightwish is far more stationary, which probably suits both their music and their fans. It was a much quieter night than Sabaton had been, no crowd surfing or mosh pit, which made it seem like a step down of an experience.
Nightwish's screen is not bad, but it doesn't have quite the same oomph as the screens for Sabaton, which had superb screen use. There is one exception, and I'll get to it in a minute. After about 2 hours, I was into it, but I was also looking forward to the wind-down (though not the penultimate song, The Greatest Show on Earth). Then they played it. As noted, they only play the first three acts, the fourth is played after Ghost Love Score as an outro. The screen use for part III was amazing - the story of mankind on screen. Previously I found this song to be bloated and pretentious, with good parts broken up by boring bits. After, I am as convinced as Tuomas that it's a masterpiece (not as much as he thinks, but one of their best works). This is entirely personal as it stems from feelings of existential dread (the atavistic dread of the hunter) that had been resonating, that the shared experience of reminding me of the glory of my existence has has helped quell. So that's a huge plus.
Overall, I was thoroughly entertained and even the odd cuts were interesting live.