The quality online presence -- forums and video tutorials! -- may even be a killer feature.
Arduino centers around pre-built, (mostly) solderless modules, included libraries for doing almost everything complicated, and a high level development environment that abstracts away everything the libraries don't; this is hardly "intermediate level" microcontroller development.
I am in no way disparaging Arduino, by the way! I'm actually friends with one of the guys who develops it, and I'm convinced it's excellent. But "intermediate" it is not.
I'd say, if you want to establish a taxonomy of microcontroller development skill, beginner would include pretty much any pre-built kit that uses a high level language, intermediate would be people who either build their own boards or program pre-built ones in assembler, and advanced would involve discarding both pre-built boards and high level languages.
As good as, e.g., SDCC is, most microcontroller ISAs are just not designed with compilation in mind. When every instruction counts, incurring gobs of overhead to accomodate a calling convention just won't cut it.
EDIT: By the way, I've done a lot of development with Atmel AVR, Microchip PIC, and 8051 processors, and though the more modern RISC architecture of the AVR is leaps and bounds more friendly to compilation than the PIC, I can regularly beat AVR-gcc and SDCC for code size.
EDIT 2: I meant to comment in the above that I'm very pleased to see that the Nerd Kit doesn't try to abstract away most stuff like the Arduino kits do. "Just magically working" is fine when you want to bang something out and don't want to know how it works, but in terms of microcontroller erudition nothing beats having to bootstrap yourself.
This is true, but the AVR's architecture was specifically designed to be friendly to C. That was one of the reasons I became interested in it: after years of programming HC11s and HC05's in assembly, I had had enough :-)
For me code size has almost never been an issue (and only then when I needed to add a bunch of features without changing the hardware): the MCU memories are getting bigger all the time.
Either way it's all great - goes back to the days when kids could monitor and control things from their AppleII and C64s rather than just stringing bits of frameworks together to make web pages.
And, though I love browsing Digikey or wandering the aisles at You-Do-It Electronics -- because I already know how -- such activity also takes a bunch of time, plus you end up either buying lots of extra stuff or risking that you will forget to buy something, or buy the wrong thing, and need to make one or more repeat trips. This risk is especially huge if you're new to electronics and don't already have several drawers full of miscellaneous capacitors and hookup wire and op amps and LEDs.
So I can definitely see the value here.
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[1] One of these days I will just pick some arbitrary project out of Make magazine and follow the little steps. Or perhaps I will buy a NerdKit!
But this is a great beginner kit and I enjoyed looking through the projects that people have built using it:
That's great. What you start with doesn't matter so much, because once you've grasped many possibilities that one kit allows, you've also built the confidence that, yes, you can learn and you can do. Then you can explore other areas with that confidence. MM & breadboard can conquer all!
I'm one of those weirdos that think that analog is more fun than digital, but it's certainly important to be exposed to both sides.
