Have used the bag on two weekend trips. It fits enough clothes for two days, including shoes and extra race clothes. The bag is super stable and you don't notice anything while cycling. Also looks very good and professional ;-).
I have replaced the bag on my last tour against the Ortlieb Handlebar Pack, because I wanted to have the handlebars times free, since I only drive from hotel to hotel. It can be packed much "tighter" and faster and is relatively easy to attach and sitz very well. Unaccustomed was only the "sprint", which is somewhat unusual with the bag, due to the inertia at this position. However, in my opinion, the handling on the bike is on balance better than a bag on the handlebars, if you have to decide for only one.
Used for 3 days on a bike tour with friends, nothing to complain about, perfect bike behavior even when dancing. Doesn't interfere with pedaling at all.