Huge Symphogear fan here, so don't expect a very unbiased review. Although I can't imagine why you'd be watching season 5 of Symphogear if you didn't like the first four unless you're one hell of a completionist or are being forced to watch against your will (which isn't an entirely unrealistic scenario given the intensity of Symphogear fans when trying to get others to watch).
The story of XV is more of the same yet completely unpredictable because "more of the same" in Symphogear means more batshit insanity and over-the-top action and badassery. Without spoiling too much, we get new villains this season who somehow tie back to villains and characters in previous seasons in some way shape or form but have their own unique and independent motivations for trying to stop the Symphogears. Much like in AXZ we get a set of three rival girls who it's hinted aren't actually as evil as some of the crimes they're being made to commit and may eventually befriend the protagonists. This is pretty par for the course in an action-packed magical girl show. Other than that, there's not much more I can say without spoiling anything or not knowing what the hell I'm talking about. I don't watch Symphogear to analyze a deep story, I watch it to get hyped up and I honestly don't care if things don't always make sense or the story has some asspulls. Symphogear is pure hype and insanity and best just to go in with the mindset of being along for the ride.
The main 6 Symphogear users and supporting cast are already well established from previous seasons. As with previous seasons, each of the girls will get her own battle song and they'll use the power of friendship and stuff to kick ass. Side characters continue to do their jobs like Genjuro providing occasional comic relief. It looks like Miku might possibly be playing a bigger role in this season than previous ones, but that remains to be seen.
Art and Animation: 10/10
This is an easy 10, Symphogear from G and onward has always been one of the most visually impressive shows when it comes to well-animated action sequences. You can feel the power and intensity behind each and every one of the characters' attacks and the fights are always well-choreographed. The transformation sequences in this season are hands down the best magical girl transformations I've ever seen, topping even the amazing transformations in previous Symphogear seasons. Watching them gets me hyped up and makes the girls look like they're ready to kick some serious ass.
The music in Symphogear is still fantastic and the girls' songs always provide a fitting soundtrack for the insanity happening on screen. As usual, if they get hit or have to put a lot of energy into an attack while singing, you'll hear it in their voice. Only reason sound isn't a 10 yet is because I haven't heard a song yet in this season that I'd put in my top 5 Symphogear songs. Maybe one of them will grow on me or a new one will blow me away but right now there's nothing to rival my favorite songs from GX and AXZ in this season. I also really miss the ignited arrangements and it looks like we won't be getting any of those from this season either.
Symphogear is the most hype, most badass anime I've ever watched and so far XV hasn't let me down one bit.
I've never given a 10 to a not yet done airing series before but I have tremendous faith in Symphogear as I've given three out of four of its previous seasons a 10 (GX got a 9 for being slightly slow-paced by Symphogear standards but I still loved it. Also note that slightly slow-paced by Symphogear standards isn't slow-paced by normal standards in the slightest).
If you're a Symphogear fan, there's a very high chance you'll love this season as much as the previous ones. If you're not, then you're probably forcing yourself or being forced to watch Symphogear anyway at this point and I can't stop you, so why bother? If you haven't watched Symphogear, go start with season one right now to see what all this hype is about and if the show's for you!
Symphogear is my favorite action anime of all time and it hasn't let me down yet when it comes to providing pure badassery and insanity (with the bonus of featuring cute girls as protagonists and having some yuri-shipping bait on the side). If you feel even remotely similarly, I don't think it's going to be letting you down this season either!