Lets get to it;
First off, the iDJ3 does not support iPhone 4, it will play music from it though. Numark doesnt officially include the iPhone 4 because if someone calls while your playing a tune from it... guess what happens. My fix for that is "airplane mode". My sales engineer told me that I can record mixes to my iPhone/Pod; sorry, but that's not an option.
This is really nice for a beat matching Dj, I could easily see scratch Dj's getting bored with it fast. Digital scratching lacks the authenticity anyway, being as most discriminatory listeners can tell the difference. I especially like how I am saving a fortune on music now. I spin dnb, I order my vinyl from the UK, and it costs me an average of $9.99 usd per record, and I usually consider myself lucky if I even like the b-side. Now I spend $0.99 on tracks from my same preferred artist on the iTunes store, get my songs instantly. that is a savings of about 90%. I also enjoy saving $2100.00+ on having records cut just to play my track in a mix. Yes, that's a lot, but I used to send my tunes to an engineer in the UK, and well... you get what you pay for. Now I just load up my digital files and throw them in the mix. The VirtualDJ LE software loads pretty much all modern digital audio formats including Apples "locked tp your iTunes license" AAC files.
I use the VirtualDj LE software that came with the iDJ3, its nice, not as nice as the Pro version, but if your comfortable with 2 decks, and being limited to recording to a wave file it would not be an issue for you either. The jog wheels are crazy sensitive just like real vinyl is; if you bump the decks what happens with your 1200's?
The crossfader feels like a scratch Dj fader, the channels faders feel like they should. The response between software, and iDJ3 is seamless. Every thing I touch moves instantly in the software, and that translates to seamless mixes.
I do not like the RCA outputs, that's never a good idea in my opinion; -10dBU is terrible, there is an enormous difference in gain between that and +4dBV. Most pro gear these days can handle the conversion with a flip of a switch though. So even that complaint is negligible. Side note: Notice the intended difference between dB>"U""V"<, it does matter, exponentially that makes a difference in the equation; yes I mean math. Also notice how I am leading you to the assumption that this is not exactly "Pro" gear, it isn't.
Great for beat match style mix Dj's
Saves tons of money
Comes with VirtualDj LE
No eq for the iPod channel
No pitch/tempo for the iPod channel
No legit, Numark backed iPhone support
Digital scratching algorithms are not quiet there yet
Consumer grade RCA audio outputs (-10 dBU)
***If Numark came out with an app for iPhone/Pod 3 of the cons I listed would be gone. Because like the "other" Dj apps on iOS I am sure there would be an eq, a tempo/pitch adjustment. and Numark would support it. If that happens I would easily change this to 5 stars.