I love it when Adobe does the Beta tests for Lightroom. I'm still using LR3, had skipped 4 and looking at 5 for my next upgrade. I've just done my first test photos, it works fine, lags a bit here and there which comes across as slower than LR3, (I just installed OS Mountain Lion 10.8.3 system software on my iMac which could be part of this. The noise reduction seems about the same as is the sharpness controls, there may be differences I don't see yet. I've only done three photos and already miss LR3 because I guess I know it so well and anything new is, well new, you have to get used to it. What is very fun and very useful is the Radial Filter, I am amazed how well it works plus the controls, and it saves a lot of time for me as I often shade areas beyond the center of interest using the brush. The spot removal tool so far leaves too much of a circle, I played with the opacity but on something a little larger I had to go to the brush to soften the edges, but it could be me and not the software. I haven't tried using the spot removal as a healing brush yet.
For me it'll be a big deal if they can improve the noise reduction even more than what it is now, with cameras having new sensors to help this along, I doubt I'll be buying any of them very soon, keeping to my IDMKIII (lordy I love that camera) and if I can get another stop of ISO noise reduction, that would be pretty wonderful. I often shoot at ISO 1600 and 2400 when doing even and street shooting, plus I really like shooting outdoors in the city just as the light drops off while the city lights are coming on. Kind of magic. Extra noise control (which is already excellent on LR3) would be a plus. Granted Adobe tends to put that till the last with these Beta tests if I remember right.
Okay I'm back and just tried the spot removal tool as a healing brush and it's going to totally rock but I have to get used to it. One thing I ran into repeatedly all ready is that the place being healed tends to come out darker, and I did try moving the selected area to clone or heal (tried both) and eventually had to live with it and then take the brush to lighten the areas up 1/10th of a stop and soften it a bit to blend it. I tried with the opacity which helps but so far I'm hoping for a little more control or something, not sure quite what to ask for.

