I have the 32LH30, and its been a very nice TV in my opinion. I've been using it as a monitor for about 6 months now and its been great for that. The only problems are ones inherent in LCDs (namely black levels, although the ones on it have been about as good as I've seen from an LCD, with exception of the 20WMGX2 that I had just prior). I prefer a glossy finish myself, but aside from that and ideally having higher pixel density on a display that close, its been great.
The speakers aren't terrible (nor are they stellar), but they would be much better as a TV than a computer display as they basically use the wall as dispersion (they shoot out the back and sides versus being on the front).
I don't believe they made any drastic changes between the LH30 and LH40 (I believe just added the 120Hz capability).