Mac OS X 10.5 Leopard: the Ars Technica review
A ludicrously in-depth review from John Siracusa. It’s definitely the best (and most complete) review you’ll read, if you can get through it all.
For those of you not willing to read all 16 pages of the review, here’s the short version: He considers it to be a rock-solid foundation and a definite step in the right direction, even if there are some sticking points along the way.