I got one of the 4 channel ones last time it was here, and at the same time my business bought their 8 channel unit direct from zmodo. I learned quite a bit from the experience:
1) the stock cameras are low res. They're 1/3" CMOS, and are low resolution and noisy. I was expecting this though for the price, these are $25 cameras. When I was discussing the 8 camera unit with their rep, she did say they were lower quality and recommended going for the better cameras, but for our use they were sufficient. You may need to replace one or two of them with better quality in key locations.
2) The cables for the cameras are generously long, we had no problem placing them everywhere we needed, and was a MASSIVE improvement over our previous surveillance system.
3) the mounting posts for the cameras are aggravatingly difficult to aim. They are on a ball joint that doesn't turn in all directions, with a metal-on-metal thumbscrew that is difficult to tighten and slips easily. Once aimed, we had to go around with a pliers to get them to stop slipping.
4) WINDOWS ONLY for remote (internet) viewing, unless you want to use an ipod/ipad/iphone. The network connection uses active-x and will only function on internet explorer on windows. We are a mac shop, so this really sucked to find out the hard way. I'm sure the windows users are saying "so what's the problem?" but the rest of us are saying "spank you very much".
5) "all weather" MY ASS. Zmodo doesn't consider "temperature" to be weather. (really??) Read the fine print on zmodo's web page, because they don't let you in on this little gem here, their cameras are only claimed good from about +5F to +120F. I live in iowa, and it's below that outdoors about 2 months of the year. The cameras start flipping and otherwise misbehaving at lower temps. They do offer cameras with heaters in them, but they're a great deal more expensive (6-8x) and require additional power.
6) out of the box, one of my four cameras worked for about 30 seconds and then never again. Zmodo quickly sent me a replacement camera without even requiring me to ship back the defective one. Then as winter approached, two of my four cameras started going flippy at 25 and 38 degrees in an indoor unheated area. Those I had to send back in, and used the opportunity to upgrade to a higher resolution.
7) customer support is good when you get it, but you can spend a very long time on hold. 15-45 min) They offer online chat support also with good hours, but despite having an option to speak with sales OR tech support, you will frequently get salesmen when you requested a tech, and they aren't too good with technical questions.
8) the DVR software is pretty good. It comes with a mouse, and you supply the VGA monitor. (don't need a keyboard) Boots up fast and appears reliable with good configurability, including motion triggered recording with definable zones within the image. The only issue I've ran into is some changes require a reboot, and a few of them don't TELL you this.
9) nighttime performance is good. Illumination range is good with the built-in IR lights, you can get cameras with longer range but these work great indoors in a dark showroom. The IR leds are highly visible to the naked eye when on, making a very noticeable ring of red little lights around the camera lens, which draws attention to the cameras. You could consider this a good thing or a bad thing depending on your point of view. They're NOT covert at night if you're concerned about vandalism or people trying to avoid being recorded.
So I'd summarize with "Worth it for the price, but make sure you know what limitations you're getting into."