This is the game's weakest point for new players. GC was never a "cutting edge graphics" game, but it makes up for it with charismatic character designs, which include the much improved art from the later reworks.
The enemy variety benefits from so many years of incremental content updates, and most of the time their attacks' range, super-armor and patterns are properly communicated to the player. Some animations are a bit choppy (specially Grab attacks), but the combos, special attacks and effects range from serviceable to cool enough to give you that rush when that hail Mary gets you the win. There are many options to customize your character with cute (or not) appearances, according to your preferences. I will always miss my collection of unique items/junk.
Only the "best" detail option with its thick black outlines allow you to see clearly when an enemy has super-armor (red outlines).

Visuals: 6/10 (10/10 if you're looking through nostalgia glasses)
The resolution options can't correct the low res textures. Beautiful character art!

Like the visuals, exactly like they were on the original game, for better or for worse.
Each continent has a theme song, and they're all serviceable, although some of them are repetitive. In-game songs are pretty good, if a bit bland. (One is almost identical to Naruto's Raising Fighting Spirit). I can't help but adore "Hope" even without understanding the lyrics or really liking the style. Some other songs are downright amazing, always getting you hyped, like the Heroic mode theme.
Sound Effects work as intended, while being a bit generic, too. But they allow everything to be easily understood and reacted to.
Voice acting (Brazilian Portuguese) is perfect. There were many things that bothered me when they re-dubbed it way back when, but I've gotten used to them after so long.

Sound Design: 7/10
Works sufficiently well within the confines of the game.

This is the title's bread and butter, where most of the charm and attachment comes from, each character's gameplay working in tandem with their visual design and voice acting to captivate players.
Simple, yet deep gameplay with many "advanced mechanics" discovered by the players through the years. Fun and challenging PvE (in the later levels, at first it's mostly single-player content), with sufficient variety and unique mechanics to try and keep things fresh (although sometimes missing the mark and making them annoying, such as some dungeons in Xenia)

You control your character in a sort of platformer game, using Z for basic attacks. Including: combining the Z with directions to use different moves and combo routes; running; jumping; charging Z and/or pressing ASDFG shortcuts for the special skills; pets, potions, weapon changing; movement; team composition.
The characters have varied gameplay. MP, AP and hybrid skill systems. Melee and ranged.
Each character has their own gimmicks, strengths and weaknesses, providing many options.

Gameplay: 10/10
All in all, the gameplay is the best part of the package in my opinion.

Monetization and Systems
They readded the GP (in-game currency that you get for playing) equipment tab from the store after launch, including the chance for epic grade equipment
There are many ways to acquire a small amount of VP, and lots of VP items are also available through P points, which you get for being logged in for 30 minutes, resetting daily.
Yet so many advantages are achieved through VP alone. Lots of (very strong, somewhat game-breaking) pets were only obtainable through spending real cash.
The Fourth Bar of MP/AP is a quest that you START at level 70 if you're a FTP player, but you can reach it as early as level 10 if you use 3000 VP. Basically the same for the ultimate Skills. Every job change is attainable through both methods (VP and GP), and while VP is instant, the quests aren't all that time consuming or difficult.
Some Skill Tree sections were locked behind a paywall in the past, but they are unlocked.

I spent lots and lots of money on CASH (VP's previous name) in the glory days, and I'm quite worried with the direction the game will take. There were many overpriced and shoddy monetization practices way back when. Some gacha/loot box elements are included.
I wish the monetization focused on visual/vanity items and convenience, like the mobile game.
But most of all I ask for Regional Pricing. VP is way too expensive for most of the player base, it's like they don't want our money. They'd make so much more if it was affordable for us.

Steam Systems
Almost seven months in and it still doesn't include Steam Trading Cards, Achievements and the like. The previous release available on Steam had the trading cards.

Controllers and options
The visual options are limited, but sufficient in my opinion. The new resolution options are welcome and they have made changes to some textures (monsters, mostly). Customizing controls is pretty easy, and configuring a controller was equally as accessible.

Whether you're a returning player, a new one or maybe you're coming from the mobile sequel, I can't in good faith recommend trying out this game right now. It's still free, so it might be worth a shot, maybe you'll have lots of fun. But... The account invasion problem and how they're handling it If we can even say that they are, since they have given no signs that they are aware, that they will solve the issue or help the players that were affected. Instead, they only help once and then say we should take better care of our Steam Accounts... But that's not the reason we are being attacked. It's their fault.

I love Grand Chase, from the bottom of my heart. With all it's charm, personality, mistakes, bugs, everything. Despite its flaws, it is my favorite free to play game ever and one of my favorite games period. I'm pretty close to 400 hours played even though I have a job and study at a university. Many people played more than me and reached much higher levels, but I always try to make time for it and enjoyed every second I'm playing.
Like an old friend, I welcome it with open arms... But I'm deeply concerned about its future.