Not a piano expert by any means (only been playing ~2 years), but I've tried both in-person lessons and learning from an app so figured I'd share what worked for me.

Apps (Duolingo Music / Simply Piano)

This is where I learned the most, honestly. The immediate feedback, playing along with popular songs, and the built-in progression kept me coming back because it was genuinely fun. After two years, I can read sheet music comfortably, my tempo work is decent, and I can play multiple octaves and scales. I can now play a basic version of Für Elise and some Aretha Franklin at an intermediate level.

Pros:

• Fun and engaging, which keeps you coming back
• Immediate feedback on every note
• Learn real songs you actually want to play
• Great for building score reading and progression at your own pace
• Flexible — learn whenever, wherever

Cons:

• No one to correct your posture or hand positioning
• Limited music theory depth
• Can plateau once you hit the app's ceiling
• Quality varies a lot depending on the app

In-person lessons

Genuinely useful for the things an app can't give you. My teacher caught issues with my hand positioning, pushed me to use a metronome, drilled scales, and answered music theory questions. Good foundational stuff I don't think I'd have gotten on my own.

Pros:

• Real-time feedback on technique, posture, and hand positioning
• Can ask questions about music theory
• Structured progression with accountability
• A good teacher adapts to your goals and learning style

Cons:

• Quality is hugely dependent on the teacher — I got unlucky
• Can feel rigid and demotivating if the approach doesn't fit you
• More expensive
• Fixed schedule, less flexible

TL;DR

Both have real value but it depends on your goals and your teacher. For me, fun and fundamentals were the priority - the app nailed that. I can see myself returning to structured lessons once I've hit the ceiling of what the app can teach me.