I love my WM Ultralite! With extra clothing (i.e. all my insulating clothing) and a warm pad (the sleeping pad is vitally important!), I've gotten down to 15*F with it. And I sleep cold! For me, the best part is the draft collar--I can snug it up around my neck and leave the hood relatively loose for ventilation (while wearing a fleece balaclava).
You do want to treat it with care, though. You want to treat any sleeping bag with care! No draping it over thorn bushes or dragging it over rocks. No letting your cat or dog sleep on it! Actually, that's true with any gear.
Feathered Friends in Seattle also makes equally high quality bags. Marmot's line of sleeping bags named for elements (such as the Helium) are also good and are more apt to be on sale.
With any sleeping bag, pay close attention to the girth measurements. (Remember that shoulder measurement is over your arms, and should also be over your thickest insulating jacket.) If the bag is too narrow, it will not only be claustrophobic but it won't be as warm because you'll compress the insulation. If it's too wide, you'll be spending a lot of your body heat warming up dead air space.
Have you tried searching the forums? There is a lot of info on sleeping bags and other gear items. The search funcftion here is a little tricky; instructions are in the "sticky" thread at the top of the General Discussion section. Pay special attention to changing the date parameters.
You can also click the items in the left hand column in this page which will take you to our TLB sponsors. You'll find lots of information about specific brands there.
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey