I finished Infinite Wealth a few weeks ago. Took me right around 60 hours for a NG playthrough, so definitely the longest game in the series. Overall, it was very good, but with some caveats. Played it with Japanese VO and English subtitles as I'm not a masochist.
Anyway, few items to note:
-Combat system is just incredibly fun. There aren't a whole lot of RPGs that could force me to grind for this many hours but not mind.
-Characters and interactions are done very well. You end up with 10 characters across two parties, and you're gonna care about all of them. I did every single interaction, every link, worth every bit of time spent.
-There's a lot of grinding. Of that 60-hour playthrough, I'd guess 15 or so was grinding in the two dungeons to get my parties up to par to do the main story missions. Some strange balance also, one mission would be dead-on for recommended level and then the next one I'd get annihilated unless I leveled up to 3-4 above the recommendation. Luckily the grinding wasn't too bad, see above.
-The main story was kinda weak IMO. I very much enjoyed seeing the fates of individual characters especially in Kiryu's portion but then getting back to the overarching plot and finishing that up was boring by comparison. Stretched too thin.
-(bizarre item here please indulge me) In the Japanese VO, Bryce's voice actor was just a terrible choice. Bryce is required to speak English for a handful of pivotal scenes, and the VA could barely do it. Zero feeling to his English lines, most of which are meant to emphasize how terrible he really is, but the VA sounds like he's reciting from a text he literally doesn't understand. Just weird and easily the second-worst VA casting RGG managed here.
-WTF with the decision from Sega to make NG+ paywalled? Loved the game but no, I'm not giving you $20 extra to skip a bunch of cutscenes and run more dungeons for a couple more achievements. Bad.
-and, finally, I hate to say this, but kind of following up on the story not being all that good, the ending doesn't really fit the ENTIRE REST OF THE SERIES. Kiryu spent like, 8 games trying to hide his identity in order to also hide all of the orphans but in this he kinda Iron Mans it up at the end? Eeesh.
So yeah. Game is incredibly fun to play, excellent mechanics and moment-to-moment writing and then it has BS monetization, a retarded final boss, and a WTF send-off for Kiryu. It's worth playing for sure but be prepared to be irritated by the story at the end IMO.