I have started this post a few times now, but it kept ending up as a rant, hopefully this one is balanced.
Having owned a Netduino plus (v1) for a while now, I'm probably a little biased, but I think its a great platform to enjoy building with.
You write your code on the free tools, download it and run it. If you want, you can write it all yourself (my preference) or pull in libraries etc. from the community.
One thing I have noticed is the lack of second hand Netduino's for sale on Ebay (at least in the UK), I was really lucky to pickup a pair of plus 1's just after the plus v2 came out - since then I have never seen another one for sale. I think that means people hang on to them. (Maybe its different in your country......)
Ok, there are some issues; I was forced to upgrade the firmware to fix the ethernet bugs, but it was fairly straight forward. I have found that when things do go wrong, or when you need to tackle something new, we are all using the "same" system - this means that help from this forum (and others) actually helps.
In contrast, I have recently acquired a Raspberry Pi (surprise present). I'm sure you will remember the Pi being launched and it sounded like a Netduino killer - all that RAM, speed and peripherals. Why would anybody ever buy anything else again?
I decided to attach it to my Netduino powered buggy. The idea being that I can connect the two via wired Ethernet (which does not use any extra GPIOs), and have the Pi present an interface to the world over Wifi.
Sounds simple, but the Raspberry Pi is really complicated to setup and use. While I am writing this, I am waiting for the Pi to update hundreds of bits of software I've never heard of - its taking ages. I'm only doing that because the instructions I found to install a web server failed. I can't tell if the instructions were bad, if my Pi is not setup correctly, if its not compatible with the instructions, or anything else. (Several others who followed the same instructions chose to respond to the article with a volley of four letter words because they managed to kill or lock up their Pi - I have never seen anything like that on the Netduino Forums.)
There are just too many varients of OS that the Pi can run, and too many possible packages to chose to run on it, some may or may not run on some OSs, etc. So when you ask or look for help, it seems to me to be very unlikely you will find a solution that works for you.
Even the really simple things are really hard to sort out, like how do I get my code to execute without logging in, or like the Wifi turning off when a live ethernet cable is connected to the Pi - that took many hours of trying different hacks to fix!
Oh, and you can't just turn it off, you need to run a command to turn it off and then pull the power.
I'm starting to rant now!
So all I wanted to say is well done to secret labs for bringing us the Netduino.
I hope there are many more developments in the future.