As Apple states in the release notes, 1.6 is supported on 64-Bit Intel Macs only. This says, that Apple does not support other Apple-architectures anymore: We cannot expect Java-developpers to downgrade for all the future to 1.5 for just one specific OS. We‘ll loose viable applications due to the lack of support from Apple.
A remark to “used for less than a month": I‘d like to use 1.6, but I cannot since it doesn‘t exist for most of my machines. 1.5 works so far - but it‘s not an excellent implementation, too.