Reason is possibly the most fun piece of music software out there. It is a VERY powerful DAW (digital audio workstation) unlike any of the others. First it has a mixer that looks and behaves like a real-time studio. Perhaps the most fun feature is the rack. You can add and take away LOTS of fantastic devices that come prepackaged, plus you can purchase other rack "extensions" as they call them.
Yes, you can record audio and midi with it. I like to use it rewired to Logic. With Reason 7 (due out soon), you can also plug in external devices.
The primary synthesizers are Thor, which has a seemingly limitless amount of possibilities of combinations; Subtractor, a basic subtractive synthesiser; and Malstrom, a graintable synthesizer. There are a couple of great drum machines, samplers, and lots of ways to mangle sounds.
You get to the back of the rack in order to plug in virtual cables to route the devices anyway that you wish.
Did I mention that the interface for each device is VERY intuitive?
Also, if you aren't familiar with how synthesis works, the tutorials that come in the manual are excellent.
The downside? Wave form editing isn't really a feature of this DAW. No video capabilities. It's designed for electronic music genre. However, I work around the latter by rewiring it through Logic. No problems.
Also, I think that Propellerhead must have the most amazing engineers. You can pump a LOT of devices into it without maxing out your cpu.
Oh, and it gets used as a live device quite a bit.
If you want to see it in action, contact me at: email@example.com.