Does anything work on Lightroom 4?!

Question

As the title says! There seems to be masses of problems with it. I've just received my copy of Lightroom 4 upgrade disk and, after looking at this forum, I'm really unsure about actually loading it in to my iMac. I'm happy with Lightroom 3 and don't want to get into problems as I'm not savvy on such matters. Will my existing Lightroom 3 catalogue complete with edits, keywords, etc remain intact and accessible to me in 2010 format when running Lightroom 4? I don't want to have to re-edit thousands of images to look ok in 2012. What do I have to look out for when installing it? Will I be asked anything that make it important that I make the right response for my needs? Do I need to create a new catalogue just for the images that will be imported into Lightroom 4?
Incidentally my iMac meets the system requirements for the software.
I'll be grateful for any help and advice that you knowledgeable people out there can give. Thank you.

Answer 1

Let's just do a cool risk assessment:
Google for the top x bugs which still exist in LR4.1RC or are newly introduced into it.
Then Altea FR needs to decide how many may possibly affect her/him.
Obviously as no Flickr user this bug cannot hurt, so we can discount that from the list.
The tone curve problem: should be solved with 4.1RC - but it had bitten only people who used it in point curve mode - parametric curve edits have never been affected.
I can vouchsafe that the pre-released script did solve it - I have not upgraded to LR4.1RC yet, because my bugs in 4.0 have been adressed, so I feel no need to hurry.
Not sure if the book bug is still present in 4.1RC: it bites if you copy text from one book into another: you'll loose all layout.
So don't create books yet, or none with much text or just finish one before you start another.
And look from the other side: what would be the worst thing that must not happen to you, but still has some likelihood? What mitigation routes could you possibly think of (or ask here in the forum)?  Loosing LR3-PV2010-develop results has been answered already, tick for "safe".
Another approach: do a cautious test: export your most critical images from your LR3-catalog as a trial catalog. Include any images you suspect they might be affected.
Then let LR4.1RC just convert this trial catalog and see how it arrives.
If everything is spick & span, you could convert your entire LR3-catalog.*
Or: start using LR4.1RC for new images, and leave the LR3-catalog out of it for a while (e.g. until 4.1 final is released). Then you need to live with 2 catalogs.
If on a Mac you could even have both LR-versions open at the same time. If on Windows you need to close one first and then open the other, so the usual situation for having 2 catalogs.
(* Do not switch process version - other than for individual images where you had been dissatisfied with your LR3-achievements, in a 1 by 1 basis expecting full re-edit.)
I wish you good success, Altea FR.
Cornelia