this game whips. the design space is so huge and unexplored it drives me crazy. they gotta make more than one more class. i've done maybe a dozen runs so far and the game looks ugly but feels smooth
there's a relatively active modding community you could check out if you wanted to wet your appetite, either looking at what other people have done or doing something yourself. Most of the fan-characters i played felt pretty shabby but a lot of them were pretty cool feeling as well.
The game reminds me heavily of a game i was super into a while ago called "deck de dungeon" which was i think originally japanese and had a really bad translation and seemed pretty unpolished in general so i wasn't ever fully aware of what was going on. Both are essentially dungeon crawler/deck builder hybrids. Deck's characters were probably more interesting, and the shared card pool was larger (the difference between characters was generally the starting deck rather than the available card pool). Deck also had a bigger emphasis on degenerate combos and on permanently adding/removing cards from your deck, the end-result being that it felt a lot more like dominion to me. Despite sinking hundreds of hours into deck, I also never beat the default mode.
What I'm looking forward to most from slay the spire, rather than new characters, is probably more content. Ascensions were good for replayability, I'm still not past ascension 6 on my highest character, but i think that what will really feel satisfying is pushing floors. Often I'll get a run that feels like an auto-win, and it is. I one-shot every encounter i get up to and including the final boss. I'd like to see how far I could take those runs if the game was longer, and I'd like for there to be more long-term deck considerations when the game tests a larger variety of things. (right now a deck that can generate enough block or enough damage gets a free pass through all the content.)
Certainly I'd like a fresher variety of characters though. Isaac (which i like to compare this game to) and Deck both had a really wide variety of characters that supported a lot of pretty different playstyles. Right now all three characters have different archetypes, but all the archetypes end up feeling pretty similar, and the differences in playstyle between the characters feels relatively small.