The game systems have aged surprisingly well; planning around citizen needs and feng shui is challenging and fun and - in principle - easy to understand. What works less well is the UI though: The game lis limited to miniscule resolutions, and a lot of things you just need to know and/or RTFM.
This game is all around amazing. From the full voice acting to the game loop, there's just nothing that's any worse than "pretty good", with plenty of elements being "amazing" or "very satisfying". Even the side quests tend to be more involved than "fetch me 15 fish" as seen in so many other games. Depending on how familiar you are with games, the first couple minutes can feel somewhat sluggish, but that feeling immediately vanishes once you're done with the tutorial and beginning areas.
Runner3 is a case of "Bigger, better, greater" in video games. It takes most elements from the previous game and has bigger levels, more content, more extras - just "more" overall. However, the devs lost the point of the game in some passages, namely in most vehicle sections. Instead of rhythm-based reaction skills, it requires you to navigate through obstacles with pinpoint accuracy. Rhythm-skills aren't required for this, but rather delicate racing control skills - which are rather difficult if you play with WASD on a keyboard. Runner3 is also more frustrating than Runner2 in that each level isn't some 40 gold pieces long, but 100. However, all levels still only feature one checkpoint. This means that learning a level gets unnecessarily frustrating as failing the jump to collect gold #96 will have you start all the way back at #50 over and over again. That it rubs it in by displaying a huge number showing you how often you failed doesn't help with this, either. The level design is mostly good, but partially questionable. The camera is moving into all sorts of exciting angles making it difficult for you to see where you go to. New enemies (that have 3 or so different patterns, mind you) are introduced in a section that has you going at 2x speed. The double jump does create a safety net when jumping too early, but in some cases, it just gets in the way (also, you can access the first bonus level (!-1) without knowing that you even *have* a double jump). There also is an annoying sound bug (?) causing the collection sound of a gold or gem to sometimes get delayed until the next beat, at which point you already collected the next one, causing you to think you missed a piece and - if you are aiming for Perfect+ - may cause you to restart. Which goes back to the frustratingly long checkpoints. All of this isn't to say that this isn't a great game that has lots of replay value. It's just that Runner2 was the better rhythm game.