After listening to the whole thing like 10 times, I've come to a conclusion.
Keep in mind that I actually like her a lot, which is why...well...yeah.
Roar - 6/10; literally one of the blandest songs I've ever heard, I can't even describe it. It's weird cause it is sort of catchy in a way but her intonation is terrible and so are most of the lyrics. And the production sucks.
Legendary Lovers - 7.5/10; this is more like it.
The pre-chorus is irritating and once again her delivery is awwwful (which is a problem for most of the album; that and the lyrics) but the rest of the song is great, especially the chorus. Actually, the chorus melody is stolen from some classical song the name of which escapes me, but it's okay because no one cares. Totally exotic in the coolest way possible, and one of the best tracks.
Birthday - 7.5/10; a very TD-kind-of-a bop. It reminds me of LFN. Super catchy, and the production and vocals (that high note!) are great. This is Katy at her strongest.
Walking On Air - 7/10; this is still one of the stronger tracks, imo. The 90s influence plus that choir = pretty great. The production is a little thin at points but it's kind of a novelty song anyway.
Unconditionally - 6/10; this song is bad in a weird way, which is the worst kind of bad. It's not catchy, the lyrics are ridiculously bad, and the syncopation. God. The syncopation. UnconditIONAlly - like, the **** is that about? Plus that awful little dripping or plopping or whatever it is sound is incredibly irritating. I suppose it's memorable for all the wrong reasons so it doesn't entirely fail. One of the weakest tracks, though.
Dark Horse - 6.5/10; so much wasted potential. The verses are amazing, the pre-chorus is great, and then...nothing. There's no chorus. Just some weak trap nonsense. And what the **** is that "rap" verse? It's horrific. If there had been a chorus and no rap verse, this could've been one of the album's strongest tracks.
This Is How We Do - 5.5/10; this gave me severe second-hand embarrassment. She is not selling it. At all.
International Smile - 6.5/10; oh my god finally a track I like. I love the stream-lined feel of this song, and the delay on the background vocals is the icing on the cake. It's catchy, it's well-produced, her vocals are layered enough to not sound silly, and the lyrics are very decent. I wouldn't go so far as to say it's single material, cause it's not quite there, but it's one of the album's better tracks.
Ghost - 5.5; this is a contender for the worst track on the album. The melody and the production (which is the best part) sound completely disconnected. She sounds horrible on the chorus, and those masked post-chorus vocals aren't even in time with the beat. This should be a rock song. She tried to make a rock song into electropop and it sounds ridiculous. And the lyrics are among the worst on the album (though that laurel truly goes to This Is How We Do; I mean her team must have been TRYING because that level of cringeworthiness does not happen inadvertently). Just...just...it's bad.
Love Me - 8/10; my favorite from the album. This is the Bloodshy & Avant track, right? It's great. Tranquil, melodic, and it makes the best use of her voice I've seen yet. The lyrics are still weak, but I love the line "No concealing feelings, or changing seasonally". Very pretty. If the writing was stronger and they got rid of the stupid pitched part towards the end, it would be even better.
This Moment - 6/10; well. I hope Robyn got paid. The song starts out fine, but then the momentum completely fizzles out when they decide to mute the beat and let Katy try some of the worst belting of her entire discography - "all we have is this moMEEEEENT", which was obviously flat and then raised a half-step. It sounds ridiculous. And what is with that out-of-breath tripe at the end? The final chorus isn't so bad since it's smothered in guitar and her vocals are layered like an IHOP pancake platter, but overall, meh. One of the bonus tracks could've taken its place.
Double Rainbow - 7/10; I've got to say, when I heard the title for the first time, I expected the worst, but this is actually a really pretty song. Again, and I'm starting to get tired of saying this, the lyrics are shockingly mediocre, but the melody is just so pretty and Katy's husky tone really works well with it. Sia could've had a little more lyrical influence, I think, but it's a sweet song overall.
By The Grace of God - 6.5/10; the live version was better. The lyrics are decent though, especially "Looked in the mirror, and decided to stay; wasn't gonna let love take me out that way". Overproduced. It takes the sincerity out.
Spiritual - 6.5/10; this song is interesting. It's uniquely mesmerizing, but at the same time, kind of bland. And too slow. But still pleasant.
It Takes Two - 7/10; hey wait this is good. It's definitely meant to be a bonus track but it's still better than a handful of the worse tracks from the main crop. The vibe is good, production's solid, lyrics are okay; my only complaint is that the chorus is a little choppy which kind of makes it less effective than it's supposed to be. The melody suits her, and the last chorus where the adlibs make it a little fuller is great.
Choose Your Battles - 6.5/10; this is a cool track. It's the closest she gets to anthemic at any point on the album. The solider-boy drumming is very cool, in the sense that it creates a kind of frenetic pace that's usually reserved for electro bops, and yet it works very well here. Her vocals are also particularly poignant on this track for whatever reason. It might be for a lack of pitch correction at parts, since most of it sounds somewhat rough. The second verse kind of sags, but when the middle-8 kicks in all is well again. Lyrics range from middling to terrible. "Cursed just like the Kennedys" / "You are my Hurt Locker lover". No comment.
Mediocre album, especially considering what she's capable of.
Moments of greatness, but weighed down by poor melodic and production choices as well as collectively terrible lyrics.
Shame that we have to wait another year though
just you wait. When Double Jesus hit those shiny #1. I mean if somethin. Like Diamodns can hit #1 why can't Double Jesus? 
A review
where are you going to buy it? I'm from Spain and it's not that expensive.