This game is a huge step-up from the first, and while not perfect, it's a game I can see myself returning to. It's more than I can say for the original.
My biggest complaint is with the story, or I guess you could say the lack of one. Like the original game, it features no story mode, and the arcade mode is what you use to experience what story there is. Unfortunately, however, the way this game goes about this is somehow worse than the first game. The winning quotes feel much less specific, and when you finish the thing, nothing is shown but one piece of artwork and credits, leaving you to simply assume what just went on. I thought this was super lame, and was baffled how there wasn't even dialogue exchanges near the end like the first game did. Luckily, the japanese-only updated version "Guilty Gear X Plus", DOES feature a story mode, and delves deaper into each character's stories, and it's great! I especially loved Dizzy (she deserves the world). Sadly, I'm not reviewing that game, so it leaves this particular version's story rather lackluster.
The gameplay is where this game really shines compared to the original Guilty Gear's. Everything has been improved, and it all feels much more balanced. Every character felt fine enough to play as, and one didn't seem a lot better than others, which is a great step above the first. Instant wins are also removed! Or at least, ones that don't win you the entire match. The moves feels smoother as well, and I found myself using overdrives a lot more often, it just felt much more fun. There was also the addition of difficulty options, which was great my newbie self. The updated graphics during the battle was also stellar! The pixel art is so freaking nice, it's very fluid snappy and helps make the gameplay more satisfying.
Along with the gameplay, the music felt more catchy and has definitely seen an improvement too! The ending themes are wonderful, the battle themes were good, and I loved Dizzy's pre-battle theme (I'm not really sure what to call it?).
It's odd, when I first played this game, it was like a swing of both love and disappointment. I cheered for the better gameplay and wonderful art, but then got disappointed for it's lack of story, but then understood the gameplay more, and found myself enjoying it quite a bit. This game was a major improvement for Guilty Gear, and I can't wait what the next game has in store!

doing my absolute best here to think of the least inflammatory way to word my thoughts on this one: when does this series get good? i thought the first game being terrible was this weird one-off where it was a proof of concept game that was an outlier for the series, but this game is arguably worse in some ways. there's no cutscenes and no endings, meaning there's virtually no context for any of the win quotes and the new characters get no characterization. the game also doesn't read inputs correctly and has some of the most infuriating AI in the game, not even getting into how fucking idiotically designed dizzy is as a boss fight. playing this game actively ruins my mood and gives me a migraine. if this is what the rest of the series predicates on, i'm heavily regretting my decision to try and play these games. they're not for me, and i question why they have the unearned positive reception they've gotten.