It works well for a lot of people, and the reason is less about the magic of 25 minutes and more about psychology. A short, fixed interval turns a vague, intimidating task into something with a clear start and finish, which makes it far easier to begin, and beginning is usually the hardest part.
The built-in breaks also stop mental fatigue from compounding across a long day. It is not for everyone or every task, deep creative work often wants longer stretches, but as a tool to beat procrastination and stay fresh, it is genuinely effective.