Breaking FFVIIR into multiple parts was the only way the game would get remade* as a modern cinematic AAA game, but I was still let down by elements of the final product that I feel could have been handled much better considering Part 1 was just set in Midgar.
Keeping Part 1 contained in Midgar was a great idea in theory, but the execution was lacking -- there ended up being a lot of filler (both in story and exploration), when there was a great opportunity to flesh out the city and the characters more. The only genuinely impactful new story beats that were added prior to Chapter 18 was going to Jessie's house with Avalanche, meeting her mother/taking her father's ID, and then stealing a weaker blasting agent so the next explosion wouldn't effect so many people, not knowing it was Shinra's fault all along. We learned more about Jessie as a person, Avalanche, and those living above the plate and working for Shinra, plus finding out about Jessie's father: Jessie thinking her father's soul was basically caught in limbo due to falling into a vat of mako was haunting. That was all really, really great, and gave me hope with what was to come... and then everything felt filler-y after that, with repetitive dungeons and a loop of 'oh, no, is Shinra evil? Yes, they are!' There was potential with the Aerith/Tifa/Cloud graveyard chapter (Aerith's fears of being alone, kids going missing, Tifa's fears of losing Marlene), but it was never fleshed out or explained fully. I had to read supplementary material to understand what was intended for that chapter, including the motivations of the final boss of that chapter, lol. I don't think filler will be an issue with the remake going forward (as there is so much content to cover, even if they remove story content from the original game), but I thought it was a real missed opportunity with Part 1 in that there was so much potential to flesh out characters outside of Cloud, and Midgar itself along with those who lived there, and the remake didn't really do that nearly as much as it could have.
Regarding FFVIIR's level design, it was a step up from FFXIII's linear literal corridor hell, but still felt very small and contained for the scope of Midgar -- it reminded me a lot of the scale of FFXIII-2 and LR, and I'm sure there is a lot of crossover in terms of dev teams. I know it's easier to make a world big with pre-rendered backgrounds, but FFVIIR's Midgar felt very, very small in comparison to the original game... and there was still a lot of literal corridor funneling! I had similar issues with level design with Crisis Core and Dirge of Cerberus, which had a lot of dull and repetitive interiors. Chapter 15 (the climb to the Valkyrie fight) was the only time I found the level design genuinely interesting. I'll be fascinated to see how the level design is handled going forward, but I have to admit I have my concerns.
TL;DR: Whilst I think breaking FFVIIR into multiple parts was the right idea, the execution of Part 1 had issues where I felt it shouldn't have considering the game just takes place in Midgar, particularly the excess filler for both story and dungeons, lack of new story beats, and very contained level design.
* (I still would have happily taken a version of FFVII with a fresh coat of paint on the pre-rendered backgrounds, updated FMVs, new character models for overworld/in combat, etc. We can keep FFVIIR's gameplay, though!)
