I have been coming to Aveda Institute for the past 3 years, and I've had all kinds of experience. I understand they are students, so I wasn't expecting too much. First time I went I had long hair, and I only needed a trim and layers fixed. I was very impressed with the result. I kept going back. I figured, you can't significantly mess up long hair. I usually like the girls and neck/head massage is awesome. I also love their products.
My unpleasant experiences involved
1) 4 hour hair cut; I understand they are students, but 4 hours is ridiculous!
2) Getting a cut too short.
NOTE: If you know how your hair behaves, make sure you clearly explain it to the students. My hair is a little wavy/curly, and has a lift. So recently when I went to get my bob trimmed, the girl kept stretching the hair to match my jaw-line - the length I had asked for. I mentioned to her about my hair type, but I feel like I should have explained more. It turned out OK - although a little too short for my liking. So please make sure you explain what you want and how your hair behaves. The girls/instructors are very understanding and they will do everything to make you feel at-ease.