I am on byetta and its been a great option for me. Have lost nearly 30 lbs and my levels are better than they have been in 4 years ;-) Its certainly better than any oral combos I've been on. That's also probably due to the fact that my pancreas is packing it in (who's isn't, eh?)
It also worked on the first dose for me - immediate results.
But...with that said, Byetta is not for everyone, some people experience unpleasant side-effects when they start. Side-effects usually go away, but its something to consider as you consider your options. I didn't have any side-effects though.
More info is available here:
http://www.byetta.com