This Christmas I picked up the EV3 for my younger son. He was on the Vex team as a 6th grade student last year. I was hoping to do more on our own since the VEX team is not together this year.
As aside note, I participated as a parent in the FLL with when my older son was in middle school and we made the trip with his team to compete at LegoLand. Last year I went to a Vex Tournament and I thought FLL was better at the middle school age group. The format was better and the kids really took pride being able to compete at LegoLand.
Back to now - My son quickly built a couple robots that are on shown on the box and the kit got shelved till last week; we have many competing activities so finding projects that would capture his interest was the goal. We found the Mindcub3r Rubik's Cube Solver Robot. This one project really was fun and got my son really interested in the kit again. For us, the project was a medium difficulty level build. It used only pieces from the 31313 kit. Everyone who has seen this Robot is amazed and he was asked to bring it to school.
Go to home depot and buy a large parts bin organizer or maybe even the DeWalt DWST14825 here on Amazon might work. It is easier to keep all the lego parts sorted and together. Before you buy any parts bin organizer you just have to make sure there a compartment that will fit the EV3 computer.
You really need to go online and look for other projects and information as what comes in the box is good, but limited. We purchased "The LEGO MINDSTORMS EV3 Discovery Book" and my son is already excited to take apart the Rubik's Cube Robot we built and start working on the workbook. Both the Rubik's Cube Bot and the projects in the workbook only need the 31313 kit.
$350 might seem like a good chunk of change to put down on something like this, they resell well on eBay if it does not catch on with your kids, but I think as a parent you have to get involved too. I recommend getting the workbook with the kit. I have been looking through the woorkbook and it has some good information and good teaching moments. We are starting the workbook projects tomorrow, so I will update this review in the future.