Maybe I'm not skilled enough to take full advantage of the LR4 enhancements. Maybe I need to fix my settings in LR4.2 and all will be well. I'm not computer savvy. But what I would say is this:
1) I had LR3 purring like a McLaren sports car. I spent the time to learn it. Bought Kelby's book (good) and Brampton's “missing FAQ” book (less useful for me) and went through them carefully.
2) Had to upgrade to LR4 when the D800E arrived. My filing system is shot. The keywords I loaded for pictures I used in LR3 don't bring up the images the way they always did in LR3. I know the photos are “there” (so it's not a pointer issue on my hard drive) because I can find the photos I'm looking for by date, but not by keyword. “Birthday” brings up nothing, but when I go by date and choose a friend's birthday, everything's there.
3) LR3 could always “find” my colorspace external hard drive when I plugged it into the back of my Mac. LR4 finds it 40-50% of the time (I just keep unplugging and replugging it in on the Import screen...gets there eventually, occasionally on the first go).
4) LR4 occasionally spontaneously quits. LR3 never did once.
As to the upgrade costing “only 60 quid” and that being rather less than the cost of a D800 so that makes it OK, I guess we must agree to disagree on philosophy. LR3 was released on June 8, 2010. LR4 was released March 5, 2012, after which LR3 stopped being updated. I paid $200 for LR3 (on sale), and when I pay that kind of money for software, I don't expect planned obsolescence in less than two years. Can you imagine Nikon saying "We're changing our technology so all our future cameras will not shoot the 50mm f/1.8D. 1.8G only. 1.8G costs much less than the cost of a body, so, no whinging"???
I'm going to keep using LR because I invested time in learning it, but I'm not pleased with the situation.