Our son learned it the old fashioned way with training wheels. We did not even know about these balance bikes back then. But we started our daughter 5 years later with one of these cheap wooden balance bikes. There were not many available back then and you could not find used ones. But now you can choose between dozens of brands and there are always some for sale on Craigslist. Already with 3 she was zipping along like crazy. She also used training wheels intermittently but she learned riding without them much faster than my son did.
The only thing I would do different now is to get a balance bike with brakes. Our daughter became a dare devil on her bike and crashed a few times because she could not stop.
Plus I am not sure I would go with a wooden bike again. Although painted they will take on water if left in the rain. The metal ones seem to be more rugged.
But in general I think that these balance bikes are a great way for them to start.
And yes with them growing so fast you have to change the bike latest after two years. But we hardly ever bought a new one and either found used ones on CL or got "hand me downs" from friends.