This is my favorite game ever, si don't expect objectivity here.
VS : Abyssal City is a Metroidvania with old-school difficulty, tight controls, and RPG elements, but oozing with charm.
What impressed me the most at first was the quality of the animations, just swinging my weapon or fist made me impatient to try to hit an ennemy, as I noticed right away the depth of the moves available : light attacks, heavy, launchers, aerial, combo with recovery at the end (and I'm not even talking about Spells, summons called Assits, Focus Mode and Focus Finishers...), it felt like a really good mix between Artistic design, and Game design. And this impression only got confirmed later on.
The Art in this game is beautifull, the drawings have their own style, the backgrounds are detailed, and the music is one of the best I've ever heard in a video game, and all this gives to Valdis Story a very solid identity, that of an epic tale of a war between gods and mortals, of a fantasy world with a grim and not-so-simple story.
What about the controls? Yes, they're tight, precision in your inputs is needed, be it for the fights or the platforming sections of the game. The game has a special feel to it, and you'll need to get used to it and understand why it behaves that way if you want to succeed. Mashing buttons will get you killed, as ennemies can block, dash, and combo you, and they only improve in the higher difficulties.
That being said, with RPG-elements, you character can gain up to 20 levels, unlock weapons, armors and accessories with huge effects on the gameplay (one more dash, or more magic power, etc, etc), a wide array of tools that can be combined in powerfull builds, capable of maching even the most difficult optional bosses the game throws at you.
And those Bosses are hard at first, you'll have to be patient, learn their patterns, in order to beat them, or even better, get the maximum rank as you fight them. Because yes, your performance will be evaluated, with noticable rewards coming with the highest ranks.
With the latest big update being released the 4th of may 2015, the content is huge. 5 difficulty modes, 4 characters with their own playstyle, each one of them having even more sub-playstyles depending on your equipement, and drastic choices to make in your progression, as you cannot upgrade every item to max level in one playthrough. There are also a few secret events and ennemies that will keep you on your toes if you want to find them by yourself.
Having played and followed that game since launch, I'm also impressed by the work of the devs, and the tweaks they've made, listening to both positive and negative feedback to always improve their game again and again. Not only bug fixes, but also tweaking some encounters, some rooms, some controls, adding the possibility to rebind your keys for exemple, and many many else that you won't even notice, all that while still staying true to their core design choices.
No game is perfect. But for me, Valdis Story : Abyssal City is darn close. I recommend it, purely and simply.