After the clunk kept getting worse, I put this kit on my LR3 nearly two years ago. My control arms were pretty shot, so I don't have a direct comparison to OEM quality, but the ride is slightly stiffer and there is subtly more vibration than before. Quality may be up in the air; I personally need to get around to replacing one of these ball joints after the boot prematurely gave up, but that's just one person's experience.
There have been a lot of debates on here about which is better, and iirc some have experienced failures of the control arms because the bushings were too hard and transferred too much force into the arm itself, rather than absorbing that stress themselves. When I asked this question a while back, several experienced members chimed in and recommended the RRS control arms, which are apparently a better design than the LR3's and fit just fine. It really comes down to your use case – if on-road manners are your priority, then the RRS arms are almost certainly worth it. If you want to beat them up off-road, then these may be a better option? If I had it to do over again, I'd probably go with OEM, but I'm not unhappy with these.
It's worth checking your other bushings while you're in there, my front sway bar bushings were shot and it's easy to get to while the arms are off.