It would clearly be an almighty shame if all the behind-the-scenes processing and flexibility LG has built into the 42LH4000 didn't result in some decent picture quality. But thankfully it doesn't let us down.
In fact, in many ways its pictures look quite a bit more than 'decent'. In keeping with many other LG TVs, the 42LH4000 produces really vibrant, bright colours that give images an instant attraction and punch.
I was also very pleasantly surprised by how well the set handles motion. The 100Hz engine does a good job of removing judder from the picture, for a start. And it does so without generating many processing 'nasties' (like shimmering halos around moving objects, or 'ghost' cricket balls), provided that you keep it on its 'low' setting.
What's more, even if you do find the 100Hz artefacts becoming annoying with some sources - most likely sporting events - and turn the processing off, the picture still doesn't suffer badly at all with LCD's common blurring problem.
Another thing that impressed me about the 42LH4000 was how well it upscales standard definition pictures to its Full HD, 1,920 x 1,080 pixel count. This is by no means always a strength of LG TVs, but I didn't find myself nearly as upset by softness, emphasized video noise, off-key colour tones or blocky colour blends as I'd expected to be.
Only on one or two momentary occasions during my time with the 42LH4000 did I feel that its standard definition pictures looked unnatural enough to actually distract me from what I was watching - pretty good going given the inherently ropey nature of so many of the UK's digital broadcasts.