The only game with free-roam elements apart from BADIK that I don't mind playing - because Belle has obvious experience and talent with designing a functional and interesting user experience. This is basically like a fantasy Ace Attorney with lewds. The renders are good, the 'gamey' parts are well made and actually pretty fun. Most of all, the characters are interesting and I really enjoy Belle's(the in game one) vulgar banter, which makes it all the better when she gets into a serious mood.
The only thing I didn't care for, personally are the "night scenes" where you act like a creepy pervert. I really never cared for this part of many other prominent VNs. It never felt arousing to me to do this, and usually goes against me immersing myself into the shoes of the MC(coz I don't want to be a pervert. I wanna be a goody two shoes hero). HOWEVER, even here the incessant yet hilarious poking and prodding from Belle gets me in the mood to do some stealthy ogling. Belle is truly great.
Note About NTR TAG: This is completely avoidable. Essentially, if you don't actually want to protect your sister from NTR, then NTR happens. If you do, it won't.
In summary, Long Live the Princess is worth your attention and time (and patreonship), especially given how industrious Belle is at updating.