I have to agree - the range is not what you'd expect. However, I have tested them, and they will transmit clearly at 100' as advertised, if you have a direct line of sight. Obviously, this is not practical for almost every installation, but technically the ads are accurate.
The reality is, these are very inexpensive devices, with minimal capabilities, so you really do get what you pay for. When you do get a good wireless connection, the images are pretty good. The problem is all in the wireless transmission. The 2.4Ghz band has become saturated (cordless phones, wireless internet, microwave ovens, etc.), and is not particulary well suited to high bandwidth at long ranges. But all the other devices using this frequency have driven the price of the technology way down, so again, you get what you pay for.
If it is possible for your setup, I recommend going with the wired cameras. They are simple, secure, and reliable. (Note that with only 4 channels, its very easy for anyone who gets close enough with their own reciever to see what you see!)
Unfortunately, wired was not an option for my two story house. I have 4 wireless cameras, and I have finally managed to get a clear signal from each of them. To achieve this from the one farthest from the receiver, I re-engineered it so that it now has 50' of cable between the camera head and the transmitter circuit board and antenna.
I simply cut the wires between the camera head and the circuit board, and spliced in 50' of regular old flat 4 conductor phone cord, just like the wired X10 cameras. (There are actually five wires running to the head, but two are grounds.) I then ran the cable around the inside of my garage and mounted the circuit board and antenna inside a 50 cent plastic outlet box that I mounted under a shelf, close to an interior wall that is only about 20' from the reciever. I now get a perfect signal - and as a bonus, it doesn't change as I pan the Ninja mount, since the antenna is now fixed.
I know not everyone wants to tinker with their brand new electronics, but X10 has always been a tinker's kind of thing. If you're not willing to spend any time getting this cheap stuff to work, I recommend SmartHome.com. They have excellent systems, that should work perfectly out of the box. Of course, the tradeoff is price.