Luna 70 is a great pack.
I've used my Luna 70 twice now on overnight trips, and Ive been very happy so far. The pack is comfortable and I don't feel all sore the way my old pack made me feel after a long day. One thing that is important to do is to learn how to adjust your pack for a perfect custom fit. The pack is highly adjustable and little tweaks can make a big difference.
For example, the chest strap rode too high up on my collarbones at first, but the instructions show how to move the harness up and down with the hook-and-loop attachment. I adjusted it taller and the chest strap fits great now. There is also an adjustment they recommend where you fit the metal stays to your back, which I haven't tried doing yet. Admittedly, the pack felt great the first time I used it before I ever adjusted it, but it felt even better with adjustment.
The pack has a lot of nice features: a hydration reservoir holder, the front side zip for easy access to all parts of the main compartment, among others. The top of the pack becomes a hip pack for day hikes (though a little small for a day hike up a fourteener.) I also like the pockets on the center of the pack for keeping snacks and maps.
The only thing that confuses me about packs these days is that the sleeping bag compartment is at the bottom of the pack. I tried using it recently for heavy items instead which I think weights the pack better. I would love to see a sleeping bag compartment near the top, but perhaps there are good reasons for not doing so.
Overall, Ive been marveling at how well-engineered the pack is, and all the little details they paid attention to. It really is a very well crafted pack, and I'm looking forward to trying it out on some longer trips.