RPGmaker is a powerful tool. If a game plays bad, it's on the dev. It takes time to learn it, but it would take even more time to learn unity, etc.
When I started out working with it, I've made several mistakes blaming the engine for them. There are some engine/plugins gimmicks, faults, but once I've got used to it, I rarely make mistakes now compared to constant backtracking and fixing the code like 1-2 years ago.
I even see some devs blaming the engine for their faults which myself did in the past.
Is it better than unity? Probably not. I feel like unity would be overkill for my needs with its complexity. It would require years of learning for the same gain, except maybe to have a slightly better performance. It could be an extra step to professionalism when you start codding the game yourself with very specific demands for features, but nonetheless, I like RPGM editor. It makes development easy and accessible. Everything is in 1 place.
As for features, it can do anything I need and has the same features and more than any other standard Renpy game has except the text rollback function which is possible but not worth the time adding.
I have custom message box with changable graphics during the game. Moving mouths, blinking eyes, nameplate change depending on who talks, saving and loading during messages, all the other vn functions (hide box, text log, skip etc) scene gallery, and many more. Is it a good engine for visual novel? No. But if you're interested in mixing VN with RPG or having an interactive environment, world, it's pretty good. You can even create function to travel between the scenes and clicking on pictures created on the scene to run the code. I don't use sprites and map walking myself, instead I made the game to jump around the scenes with interractions on mouse click (or finger if playing with android).
The only downside is poorer performance on very low end pc and mobiles and lack of proper preload tool. The engine loads graphics and audio on demand instead of preloading on the scene which makes stutters, but it's only noticeable on very low-end hardware (or rather the hardware which needs replacement). There are tools for that, but I never invested time on that. Some didn't work with my project running with 200 plugins and I dropped the idea. It's not a big issue. The other issue is that it performs poorly with full HD 1080 because of how it draws the graphics, but it's fine. As a dev I have to consider file size too, so 1600x900 is fine for me.
These are probably the only two issues I have and the first one is probably fixable with more time investment.
Rpgm features are rarely used to their potential especially in porn game development/projects. To repeat my opening sentence, poor gameplay is on the devs.
The engine is capable of pretty much anything.