It must be just me, but I'm like a kid in a candy store with Logos 4.
- All these new ways to do things more efficiently.
- Seeing more information, more easily. That new information windows is great!
- Easy data backup
- Better window management including multiple monitor support
- Intuitive searching including autocomplete to help me with my bad spelling and speed.... this thing is FAST!
- Great new resources at bargain basement prices in the upgrade
- Resource prioritisation and tagging
Sure we're waiting keenly for a number of things, but getting Logos 4 this week was like Christmas early (or late given NICNT/NICOT was my Christmas present in advance). I was expecting to wait until late 2010!
If you don't have time in your schedule now, wait a while until you have a break... but maybe take advantage of the upgrade discount while it lasts 
If you don't like change, wait until Q1 or Q2 next year and borrow a copy of "Who moved the cheese?" while you're at it
Because you are going to have to change the way you do a lot of things....
Either way, let's keep the feedback proactive because Logos has obviously listened very closely to their users and we wouldn't want to dishearten them by being unthankful!
Thanks Logos for your great work in enabling me to immerse myself in the Bible that little bit more. I know the fruits will be seen in years to come wherever God takes me in ministry!