I purchased the 990 in late 2005 and the military has kept me so damn busy I have not had the time to do any of the firmware updates.
I finally have the time now and just wondering if it's worth it and what all does it change? I have everything set up perfect now and don't want to screw it all up.

Worth it? I could not say. I have had my 990 for two years now and I am very please with it's performance. I understand that if you are big on two channel listening there is an improvement. It does not improve your listening pleasure with a Home Theater environment.
I also have read that there are people out there who have had some problems with the upgrade. No fault of Outlaw.
If you are computer literate then you are not happy with the current 990 experience then go for it.
Me. I believe in the old adage "If it ain't broke don't fix it".

I've got a separate firmware update page that may interest you. What version are you running? If it is the original 3.07, I'd definitely upgrade. If you have 3.11, then the move to 3.24 fixes some bass management issues that may or may not have affected you.

I purchased my 990 in Jan 2006. I upgraded later in the year to (I believe) 3.11. The upgrade was definitely worth it to me for resolving the bass management issues.

Rob

I purchased my 990 earlier this year and updated the firmware to the latest revision immediately. I have had no issues with it, although I've not used every available feature the 990 offers.

Thanks guys. How do I check for what version I have now?
Also what bass management issues were there before the firmware?

My firmware update page has instructions for checking the version and a detailed list of the changes included in each version.

Thanks as usual Gonk, should have read your page first.