It gives bogus keyReleased events when you hold down a key. There is basically no clean way to know that a key is being held as opposed to being tapped repeatedly.
Been VERY busy with a huge move guys, sorry, will be better involved again next week.
As to the rationale:
(1) For the record, Sun didnt invent JInput. Its was develoepd by the JSR134 expert group which included folks from many different companeis including Sun, Sony, BLAM!, EasyStreet Games, and some other odds and ends.
(2) The goals on JInput were to have a generic input model that was extensible across all reasonably predictable input devices, gave polled IO, was cross platform, did not require AWT to be loaded, and did controller discovery.
At the time NONE of those present in the expert group knew of an existing solution that did this. Given the hundreds of thousands if not tens of millions of OpenSource projects that exist on the net today, I don’t think you can fault them too badly for not being aware of every possible one that might
pertain.
Of what we in the EG DID know of, generally there were one of three problems: (1) Not cross platform (straight DX bindings), (2) No support for generic input devices (Joystick, or in some cases Joystick and mouse), (3) No discovery.
As for existing OpenSource input projects I love hearing about them as my feeling is any good ideas and/or code leg-ups we can get from them the better 
I really feel a need to stress that these aren’t “Sun’s APIs” here at java.net. If they were, we wouldn’t be releasing them this way. These are intended to be YOUR APIs (the java.net community.)
If the community as a whole decides that they’yd rather throw away the work we’ve done to try to assist and jumpt-start this and move to something else, thats fine. Thats one of the reasons why we have an open community of projects. Don’t like ours? Start your own!
JK
P.S. As for a porting guide, I recognize the need. I’m up to my eyebrows in alligators right now though. If someone else wanted to do it I’d be happy to support as I could through email. Otherwise its on my list to do WHEN my schedule clears a bit.