It effectively lets you live outside if you really wanted (save for a bathroom and a bedroom, but the latter can be fixed with WA expansion). Living Room through the portable stereo, chairs and huge TV, kitchen, plus general outdoor stuff like the loungers, benches, firepits, and hot tubs. The stuff isn't always the cheapest, but if your family can afford the stuff, it looks very nice. There are two major themes for the set: iron-wrought and stone/brick.
Celebrating over 10 years of the Sims
All of Sims 1 save Hot Date
All XPs of Sims 2
All XPs of Sims 3 + OLS
Yes! Especially the outdoor kitchen is something I really like. With Seasons to be released within a few months (and maybe Sunlit Tides to download in store) I would definitely purchase it when it's on sale (I believe it is currently till the end of august).