I really love my TH30 Combo, I actually prefer the clean channel to my Fender Blues Deluxe, so much more open and in your face.
As for the dirty channel, its so so versatile you can dial in so many sounds what with the 4 stage gain and shape control.
If you go past the 2nd gain stage (ultra, ultra high gain) then it starts to get fizzy, if you dont play metal then you wont be going past 12 o clock on the gauge period.
You DO need a good 20 mins alone with this amp to find the sound you want as well as a room where you can crank it else you wont get a good idea of sound you can get. Too many people try it out with the gain on 12 o clock - maximum and never really dial in a great tone. I play highish gain modern rock and i have the gain at around 10 - 11 o clock and i get a great crunch thats harmonically rich and articulate.
I retired my £250 Exotics BB + pedal after being able to dial in almost the exact same tone with the dirty channel. My lead tone is actually better.
I would definitely recommend using a compression pedal when testing out the amp too, especially when trying out the high gain stages.
Some people moan that they are made in China, the fact is ALL Orange amp parts are made in China. The only difference is that the TH30 is assembled in China where as all previous Orange's are sent as parts and assembled in the UK. Personally I would rather save £200 by having it assembled in China. Mine is perfect, no rattles, nothing remotely loose and its built like brick sh1t house.
I got mine new for £545 Bargain.
Have a listen to the review vid here so you can get an idea;http://www.musicradar.com/gear/all/amplification/instrument-amps/guitar-combo-amps/th30-thunder-30-1x12-combo-300580/review