Nilesh Kapadia

If you are using iLife '06, I'd recommend sticking with it for a while instead of upgrading to '08. Feature-wise, '08 is excellent, but there are major stability issues that almost render the apps unusable in some cases. Here is a run-down of what I've experienced:

iMovie

iMovie '08 has an issue where it crashes when importing video from a video camera that many people have reported. You can work around this issue by importing into iMovie '06 and then importing the '06 project into '08. Not that iMovie '06 is that stable either, it will crash occasionally making you lose all your work since your last save (so save often!). Note that iMovie '06 is available for download for people who have purchased iMovie '08.

iMovie '08 wouldn't even run for me until the first update.

Update: There are some reports that this issue went away after upgrading to Leopard.

iPhoto

I've had two scenarios so far where iPhoto will crash or lock up. One was when importing a large number of photos it would crash (haven't experienced that one in a while, so maybe they fixed it in the last update). The more recent one is I'll press an arrow key to go to next photo when viewing a photo. Seems to have something to do with rotate, because it occurs when I've been rotating pictures. I will get a permanent beach ball and have to force quit. When I start the app again, I lost any rotates that I had done. It happens pretty consistently. Apparently, other people are experiencing it too.

GarageBand

I haven't had any crashes with GarageBand yet, but I find it to be terrible sluggish compared to the '06 version. The GUI seems to stutter when I'm recording. I am using a Mac Pro with 5GB of RAM, so my hardware isn't the issue. It also takes a lot longer to start '08 than '06. This is strange because there doesn't seem to be that many big changes in the way GarageBand works.

Those are the only iLife '08 apps I've used so far. Though I'm impressed by the features, I'm very disappointed by these bugs. It feels like I'm using alpha-quality software. Hopefully, Apple fixes these issues quickly. I wish I could downgrade back to '06. iPhoto is the only app that I'm really trapped in; unfortunately I've used it too much to be able to rollback to my '06 backup without significant work to catchup with what I've already done. But maybe others can learn from my mistake. I will probably not adopt Leopard so quickly, though it looks excellent feature-wise. Though there is the possibility that iLife '08 will run better on Leopard than it does on Tiger.