The best I can offer is my experience with the very similar Lambo. Stock brakes suck real bad, bike will need a tune up unless the LBS does it. If it is indeed an aluminium frame, you will find it quite stiff, but comfortable.

If it's steel, I think one of the amazon reviewers said it was a bit springy.

Can't speak to the shifters.

My wife and I, and my son and I enjoy riding it very much. My son, 6'4" rides as capt, and is very comfortable. We easily cruise at 19 - 20mph, and sprint to 30. Got him a 400 mm seat post. I'm 6' and I find it comfortable also. When I ride stoker, it's a little cramped, but not bad.

Let us know how it works out.