Works For Me
Don't want to sound Jack but whilst agreeing that it was a total clusterfcuk at the start (and for a few weeks thereafter) JPA seems to be doing the biz for me now. Availability has been "Green" for the last couple of weeks and I have my online pay statements for April and May. My tax code is 493L which should worry me (from reading the above threads) but I never understood the code to begin with so what the hell.
There are some irritating bugs that need to be addressed like not recognising shift workers for leave but hey, print it out, annotate the breakdown and stick it in the post. It's not life threatening.
Finally, any improvements didn't happen by magic. A lot of people (not just the guilty ones) have worked there socks off to get us this far and I, for one, am grateful. So thank you, you know who you are.