I purchased it a couple days ago and an VERY impressed with it.
All the apps have been given a facelift (they all have the same slick iTunes 6-like interface), adn iMove/iDVD have a much better layout.
iPhoto has some brilliant improvements -- it really is "as smooth as butter" (© Steve Jobs). I also love the calendar and greeting cards, although the greeting card templates aren't the greatest, and can't be customised much. I don't tend to do any editing in iPhoto (as I use Photoshop), but I bought a copy for my mother who does and she *loves* the new full-screen editing mode. It feels like a pro application in full screen mode.
I also dont tend to use iMove and iDVD in favour of pro choices, but I had a have a look at it anyway. I was B-L-O-W-N A-W-A-Y by the new title sequence templates in iMovie, and by the new themes in iDVD. seriously-amazing.
Apple have proven, once again, that they are the undesputed king of to-notch, 1st class templates.
Garageband was the main reason why I bought iLife. The interface is much better organised, and the podcasting thing is nice (though I wouldnt use it myself). What made the app a "must have" for me was the fact that you can now import video into the Garageband timeline and compose a music score in time with it. that rocks. I am so happy with that
I've spent a truck load of money on all 4 of the jam packs, so this will put them to good use (orchestra jam pack is the best btw. the string instruments are amazing, but you have to take advantage of the expression and foot controls to make them sound really realistic).
I haven't looked at iWeb, not something I would use. If it has templates half as good as those found in Pages or iDVD, then it should be excellent. mdnky showed me the code it spits out, and it's pretty nasty, but aside from that it looks good.
I personally think the iLife package is the best value software package on the planet by far. Surely apple isnt making much (if any) profit on it.