DFRobot 4WD Arduino-Compatible Platform w/Encoders

Only a few cons with what I received: 1.) The encoders don't fit on the front wheels unless you use extra hardware. Not a deal killer...but you have to do some thinking. 2.) The drill holes for the Arduino are places too close to the servo hole. If you put a pan/tilt mount in this space you'll hit the Arduino board as it spins around. I simply drilled holes closer to the back of the robot. Problem solved. 3.) The motors WILL require you to solder capacitors on them. Do this BEFORE you ever start mounting them to the unit. You've been warned. Otherwise...I'm enjoying it.

Most of the chassis is very easy to assemble. While the instructions are IKEA-like in their simplicity you should be able to figure it out. As mentioned by William, some of the hole placement needs to be considered but its not a big deal. Also, the screws for the encoder fans are pretty snug. Be careful not to break them. All in all, this is a very good starter kit. We are using them in our Robotics class at the high school.