I've just been and tried one of these amps out and thought that I would share my experience....
I tried a LG350 (green one) into an Ashdown MAG 115 cabinet. I also tried out an ABM500 115 combo and a MAG300 115 combo so that I could do a direct comparison.
Firstly, the sound.
It sounds much warmer than the MAG and use the eq shape button and playing with the eq I was able to get it to sound fairly similar to the flat ABM sound. The sounds are fairly versatile and it was easy to get a modern sound for some fast picking action and a nice warm tone. (I wonder what it would sound like with an ABM cabinet?).
Next, Features.
In direct comparison to the MAG, it has better eq adjustment semi-parametic over 5 fixed frequency knobs. It doesn't have the sub-harmonic, but this is not a huge selling point for me. It also doesn't have the built in compressor or a footswitch input (although this is not needed as it doesnt have the features to turn on/off!).
In comparison to the ABM amp however, it lacks the valve pre-amp, which for me is the big one. Obviously, this is what gives you the weight reduction and small form factor, so I think that it's more of a preference thing.
Next, build quality.
I was very disappointed by the look and feel of the amp. The ABM/MAG amps look really nice and feel very robust. The knobs are solid and smooth. In comparison, the LG350 front panel and knobs seems cheap. The plastic looks cheap (a little too rough around the front panel) and the eq knobs don't seems as smooth. The on/off switch seems flimsy. I would worry about breaking it.
Finally, overall comments.
I was really impressed with the sound of the amp and though that it has a very versatile tone. The eq, which scared me in the photos, was surprising easy to use to get the desired tone. The simple presets helped with this. The amp is tiny and SO light weight. It would be ideal to stick in laptop bag or rucksack and carry to a gig. If you want a simple feature set and weight it a problem, then its a great amp. Despite my complaints over build quality, I would still buy it over a MAG head (although I think I'd get the LG1000).
For me, I'm more likely to get an ABM head. It has the extra features - VALVE/COMPRESSOR/SUB-HARMONICS/FOOTSWITCH INPUT/TUNER OUT WITH MUTE - which make it worth the extra cash for me. I would also be concerned about how it would travel. Most of my equipment get chucked in the back of a van and stuff inevitably gets bashed around. I don't think this amp would last long in that situation. But if you're careful and carry your own equipment then its a nice sounding, very portable amp.
Hope this is of use.