This sleeping bag is the best bag I have ever owned, and I do not ever plan on getting or needing another one. It is warm, light-weight and extremely packable. I have used this in the snow and during the summer and slept well during both times. The fabric used in construction of the sleeping bag remains cool to the touch so it does not get hot and sticky in the summer, but provides insulation during the coldest of nights.
It has plenty of room for an average sized person. If you have a little extra girth I recommend getting a different bag such as REI's Big Agnus for more comfort.
The "Cat's Meow" is the ideal backpacking sleeping bag, it will never become a burden, and it retains its integrity even with a few minor rips and scratches that come over time from wear and tear. I have had mine for close to 5 years and I still use it regularly without any problems.
The only bad thing would be if you cared about color as it is a purplish color, so if you are a guy and feel like this degrades your manhood you may not want it, but regardless it will be a great buy.