It depends on if you get the rubber pads or mesh heads. I went with the mesh heads due to a lot of factors like less fatigue than hitting rubber over and over, nicer look, and they are very similar to regular drum heads, although I have grown to actually like the mesh OVER a traditional drum head. You can tighten them down for different tension as well as different tonal qualities so that if you want to just practice, you don't even have to turn it on, and you can get different pitches from the tom toms just like a regular set, but with a LOT less volume. Great for late nights when you want to work on technique, just like with a traditional practice pad, but better because you have a whole set of "practice pads".
As for sound quality, the thing to keep in mind there is not the sound quality of the kit's sound module, but the amp you have it hooked to. Make sense, since we are all into audio, obviously, that your sound output will only be as good as the actual output device (amp/speakers/headphones, etc). The sound samples are really good, and you have so much control over changing them to meet your needs.. You can change the sample, pitch, duration, volume (so many drummers are strong handed, but weak footed so a new player could turn up the volume on just the bass drum), sensitivity, etc. On some of the higher end modules (TD-20 and others) you can actually control the output sound by moving the "virtual microphone" so that it sounds like an acoustic set with the microphone inside the drum, above the rim, 1" away, 4" away, etc. You can change the room acoustics as well for most, if not all, of the sound modules.
Tons and tons of options that aren't available with a single acoustic set... Plus, it you want more cowbell, you can change everything to a cowbell, but will all different pitches, durations, etc and have a full cowbell set!
I had a Tama Techstar back in the late 80's, and it was VERY "tech" sounding with just adjustments in attack, delay, pitch, and noise. It was fun, but I regretted getting it after about 2 weeks. With the Roland VDrums (which most will argue are the absolute best manufactured "electric" kits made right now) they are just unbelievable.
