I see that this thread is a week old, but thought I'd give my review of the Giant Lust Advanced 2 2014. I have about 6 rides on my new bike. I'm not a professional rider but love riding and want to ride more. When deciding if I wanted to purchase this new bike I couldn't find any reviews on it, so that's why I'm giving my opinion now.
I'm 47, 5'4", 125lbs and the small fits me very well. I do have short legs and a long torso compared to most women this height.
Most of my riding is up hill, from 1000-2500 feet elevation gain and then down again. I do lots of rocky technical stuff, but never let my tires leave the ground. I'm a cautious rider and slow down a lot.
It took a few rides for me to notice the new features. I had been riding a Titus Motolite and Rocky Mountain Element for years. I am now feeling the 650 tire change and really like it. I do roll over rocks and tree roots easier and at a slower pace if I want to or need to. Before, I would deliberately speed up so I didn't have to peddle over the obstacle, this is not as necessary with the Lust Advanced 2.
Also, the gearing is now second nature. At first I was 'thinking' I needed lower gears, but now I've calibrated myself to the new gearing and do not miss the 'smaller' gears at all. I seldom need to use the smallest gear.
On the down hills I find I'm comfortable going faster on the same trails I've ridden for years.
A big difference, both up and down hill, I don't move around on the seat nearly as much. I used to really sit on the tip of my seat for steep uphills, now on the same hills, I'll stay very centered on my seat. One con, I am still getting used to the wider handle bars, and did one time nick a tree. The handling is very sensitive. My first ride out I was a little jerky, but I've really smoothed out my steering now that I'm used to the handling.
Although the bike hasn't fixed my back and hip pain, I didn't think it would. I love the bike and highly recommend it.