I started out with the PicAXE, but within about a day I came across a massive showstopper (for me anyway). Their serial port read command didn't have a timeout and there was no way to check for bytes available to read. This made it impossible to work in the background and poll for serial commands. They might've fixed this by now, but it was enough for me to move to the Arduino.

While I've not shifted 100's of devices, having to add a 50p resonator to each of them isn't a big deal for me.

There's nothing innovative about the Arduino, it's just that now it's so popular you can find people who've interfaced just about anything to them, and they're usually happy to tell you how they did it.