I want to learn Tapestry, but I read in the documentation that version 5.4 is coming soon. It's now in beta version 22.
I also read that there will be a great difference between 5.3 and 5.4 on the level of Javascript implementation.
Can I start using the beta version or do you recommend to wait until the version 5.4 is released for production environments?
The beta versions are quite stable (Tapestry code in general is quite stable). If you can accept a very small amount of risk (that there will be disruptive changes between now and the GA release) you will be vastly rewarded with what 5.4 has to offer over 5.3.