Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Fantastic - it works great!

When my sleep started to be affected by the ache in my hand, I knew that I had to do something different with my computer setup at work. I had been spending hours clutching the mouse working on a very large year-end report. When I found the vertical mouse online and read the user reviews, I ordered one immediately. I love it! It's easy to install and easy to use. I've had no problems. I love the ability of programming the buttons to meet my needs. The best part is no more aches and pains!