PRO: My first Dremmel bought on the recommendation of an experienced friend. Very happy with the performance, mobility, speed control. CONS: Too bulky for fine work when used alone. I bought the expansion and I love it. Batteries are good for some jobs. My friend installs electrical devices in cars. Great for that. I use it for carving wood and stone. These longer projects take longer than the batteries will allow. I bought a second battery and it helps, but the second battery sometimes dies before the first one is charged. I want to buy a dremmel with cord. However, this is my inexperience. 5 stars guaranteed because he does what he has to do very well.