I'm a huge fan of HS1, but I have no motivation whatsoever to download around 53 gigs of data to see what HS2 is like. It really doesn't feel any different from Ai Shoujo, a game I downloaded, finished, then deleted, because it ended up boring me. I do understand the meshes are higher poly than in HS1, but other than that, HS2 doesn't seem to bring anything new to table to ever consider it as a replacement for HS1. Unless there's some dramatic DLC that I just "must" have, I think I'm skipping this one and see if an HS3 ever comes around with something different. Would love to hear from people who feel HS2 is better than HS1 in any relevant manner, I'd love to have more opinions on this.
Hmmm... If you're just interested in the Studio, then yeah, HS2 brings nothing to the table.
If you're a huge fan of HS1 and like me found AI to be boring (i can't believe you actually finished it! insta-delete for me. Who thought minecraft with H was a good idea?!), then you'll find HS2 to be quite worth your time. It's everything HS1 was, but better.
Graphics being the huge seller, of course. But the character creator is also much more streamlined (though not greatly improved on in terms of customization, imo - without wideslider it's little more than a make-up simulator with a very narrow window of variations, but so was HS1). There's more maps, better lighting, decent optimization and a brand new feature to call random auto-generated characters for H-scenes with some cool body and personality types search filters.
Really, it's a no brainer.
I get it, after years of modding and customizing a game to run perfectly to your tastes, anyone would dread making a fresh start. If that's what's stopping you, take the leap. It's like updating your OS from Windows 7 to 10 - huge inconvenience, but you gotta move with the times. This is where the modding community is going to be spending most of their time now, you'll be missing out.
And if you're a huge fan of the game, then you have no need for the 53GB. 37GB of that is Studio assets.