Kudos to Cyan for all their fixes in the patch/update they've just released. For me at least, the game is running noticeably more smoothly.
Nonetheless, there are a lot of things that can still be improved, and day/night cycles in more ages, as discussed in this thread, would be a major example.
I, too, liked the atmosphere of the day/night cycles in Stoneship, Mechanical, and Selenitic in RealMyst. If Cyan can implement similar cycles for those ages in RM:ME, but make them more realistic (a bit longer, and more visually detailed) this time, they'd make RM:ME a much clearer improvement on RealMyst. I love the night in Channelwood in RM:ME; the large moon and the fireflies make it really something special. Channelwood in RM:ME is undeniably better than it was in RealMyst.
But, with RM:ME it feels like a few steps forward, and one or two steps back. You've improved so many things, but the loss of day/night cycles in Stoneship, Mechanical, and Selenitic, are a glaring area in which RM:ME is actually worse than the old RealMyst. It's among the list of negatives - flawed optimization at first release, $18 price, etc - that have caused a lot of reviewers to trash the game. One review site I noticed has actually posted a dismal 4/10 rating for RealMyst: Masterpiece Edition. Ouch.
This said, I think that RM:ME has the potential to become a fairly strong seller for Cyan, if Cyan will continue improving on it. Most of the complaints that have been raised regarding the game can absolutely be addressed. A lot of them, as of the first update, already have been! My advice: go through the list of complaints that you haven't already dealt with. Try to respond to them. Do what you can to clean up the game during the next month or two - and then maybe after you've made the game that much better, wait another month or two and then put the game on sale a few times, maybe a $15 sale, a $12 sale a while later, etc.
The combination of improvements to the game and periodic sales should win over a lot of people who have been cynical about RM:ME so far. There are people on Steam calling this a 'cash grab' but you can prove that you actually are committed to supporting the game and making it better I think that attitudes will become more positive over time.