Well, Bydureon is the new once a week injectable GLP-1 analog, a follow on to the successful once a day Victoza and before every meal Byetta. I didn't use Bydureon, but I did use Victoza and Byetta. They work by amplifying your insulin response when you eat. T2 is actually quite complicated and in many T2s, the signals that tell the pancreas to secrete insulin are messed up (above and beyond any beta cell loss).
So for most the major action is a better response to meals. There are secondary effects, less hunger and weight loss. Many people notice nausea when starting, but for most this goes away. For many, starting with a lower dose, getting adjusted and then working up helps.
I saw transient improvements with Byetta and Victoza. I had real observable improvements over the first couple weeks of use. After that, they appeared ineffective. I think part of my situation was that I was already eating low carb, so improvements in my meal response were minimal. I have heard of others having much more dramatic improvements.
I was pleased to see Bydureon added to my insurance formulary in 2013 as a preferred drug. As a branded drug, this drug would cost me $200/month on my insurance plan.