Sound — 7
The DM4 comes with 16 different types of distortion, each one is modeled off certain pedals. There's a list of the 16 different drives this pedal has and what they are based off. They all sound pretty sweet but when you compare them to the original there is a difference in quality, but that is to be expected. The two effects I use the most are Heavy Distortion (based on Boss MT-2) and the Screamer (based off the Ibanez TS-808), you can get an extremely high gain sound with Heavy Distortion which sounds great for Metallica and Megadeth type stuff, the Screamer is a softer overdrive which I absolutely love using when playing blues and occasionaly Jazz. Probably my favourite feature is that it has an in built noise gate, so if you want to you can cut out all that unwanted feedback.
Overall Impression — 8
I've been playing for almost 4 years now, luckily for me I got this pedal for free (here in Australia it costs about $700 Retail price I think). It is a great pedal but if you do Live in Australia and are thinking of buying one I would definetely not spend that much money on one of these, it is a great pedal but I personally don't use it to all it's capabilities and therefore wouldn't buy it again (well, buy it for the first time) as I'd rather just spend less money getting the Boss MT-2 and the Ibanez Ts-808, the two main distortions I use this pedal for. But if you read the list of its stomp box models and loved nearly all of them then I'd say go for it. Bottom line is only spend the money for this pedal if you are really going to use it to it's full potential (unless your from America, in which case it's a lot cheaper).
Reliability & Durability — 10
This thing is built like a tank, it is made with a metal shell which defends it from even the brutal stompers. I have yet to use it Live as I tend to use my other pedals Live but if I did I'm sure I wouldn't need a backup as of how bloody strong it is. It runs on 4 C batteries.
Ease of Use — 8
This Line 6 distortion modeler isn't the easiest stomp box to use, that being said you'd have to be stupid not to understand how it works anyway. The manual tells you pretty much everything you need to know and I suggest giving it a read before using it because the DM4 has a few hidden features you mightn't know about (such as an alternate Bypass mode and a noise gate).