The price of this has dropped amazingly since its release.
However it is also available on the App store as single apps (minus iWeb and iDVD) an d is slightly cheaper to upgrade a single component.
Note that you can't buy iWeb and iDVD on the App Store, so the disk is the only way you can get hold of these if they're not already installed on your machine. I won't review either iWeb or iDVD as they're unchanged since iLife '09.
Apart from a major upgrade bug in iPhoto, the apps went on both my machines OK. (iMac and Macbook both 2007 vintage).
On Lion this makes a lot more sense - you lose some features on Snow Leopard such as full screen. The edit tools are much the same - but the automatic red eye remover is really good, I used to have to to this manually often but not any more. The strip under the pictures is good too.
Not much changed to be honest, the trailer feature is fun but a bit of a gimmick and apart from a sound feature there's not much new here.
Don't really use this, some nice new lessons with more feedback might tempt me to.
So apart from iPhoto not a lot of new features, however the main problem I had was during installation - I installed and then went to software update ans upgraded 9.0 -> 9.2.0 -> 9.2.1. DO NOT DO THIS, it basically wrecked iPhoto on a day when I needed my laptop. The correct update is to install, then open iPhoto accept the software update to 9.1 and then upgrade to 9.2.1. This is very poor, as it required a major amount of fiddling around with to fix (using AppCleaner). Apple should have fixed it, and this is the first time I've seen this with an Apple application upgrade.
So worth buying, I think if you have Lion probably as long as you avoid the upgrade pain. I like the new iPhoto although I appreciate this is heresy(!)