10/10, naturally. One of my absolute favourite Iron Maiden songs (it places in the top ten for me) and I'm certainly not alone on this viewpoint. This here seems to be one of those everyone thinks is one of the best. Of course, it's perfectly understandable, considering the sheer quality on display here. The lyrics, the instrumentation and just the fun of it is what makes it such an timeless classic.
I do have to wonder, when did this become the usually-considered best song on the album? For years and years, Rime was considered the absolute best, the cream of the crop and easily the best on the album. I don't know what exactly happened, but in the last amount of years, this song must have built up some simply impeccable amounts of hype. As seen by the fact that it placed #2 in the last two Iron Maiden survivors, just behind the omnipresent #1 Hallowed Be Thy Name both times. Something must have happened here and I think personally that it's a matter of general song quality vs epic feel that has been becoming more and more prevalent in recent years. Rime is this massive behemoth of a song, as grandiose as Maiden ever got. Powerslave is this decidedly shorter but sharper song which is so sleek and flows so well. People may like Rime more but it's much easier listening to Powerslave than Rime because of the length. Powerslave doesn't bank you over the head about how grandiose it is, it just is. Therefore, it's a song you really love but love even more once you realize the nuanced nature of it. See, Rime pretty much stays in one kind of mood for the first five minutes while Powerslave has already had plenty more dynamics and gone through its entire magnificent instrumental section before Rime even gets to Act 2, which is also usually considered the weaker bit of the song. Meanwhile Powerslave smashes back to the verses and ends on such an amazing note with Bruce's amazing yell of "Slaave...to the power of DEAAAAAAAAAYYAAAAAATH!". Once Rime stopped being put on a pedestal just for its posture and grandiose feel, I feel people looked back at the song preceding Rime and realized that it was, at the end, a better song. Rime doesn't even go all the way with its repeating of the first five minutes, it just kinda ends because the story of the song ended and they just had to stop it there. It's sort of a abrupt stop, while Powerslave's ending is nigh perfection.
Or something like that.