Well, I have Leopard on my MacBook, and I figured it probably warrants some discussion. I haven’t really had a chance to poke around it in too much detail, but I’ve noticed a few things that I like and a couple that are frustrating.  First of all, upgrading to Leopard was cake. It took about thirty minutes, and everything is working as of right now. Well, not everything, but it wasn’t like trying to install a new Windows OS, and for the most part things just need time to catch up. But what was beautiful was that all I had to do was put the Leopard disk into my computer, make some very simple selections, and let it run. Since I’m probably going to be availing myself of Vista in a few months since I can get it for $5 through the university, I’ll be sure to comment on the differences. Another note: the new desktop is gorgeous. The reflection on the dock is subtle and natural, the fold-out lists reduces the amount of folder-surfing, and just in general things look great. The preview feature on documents and PDFs is a nice touch, and sometimes I find it useful when I download an article from arXiv and forget to relabel “0711.0848″ with something like “BEC gauge symmetry”. The standard bundled software has some nice updates as well. I just today switched back to using Safari from Camino, as I grow increasingly disgusted with open source software for “life” type things, so I haven’t found much new there. But the Calendar looks better, and I like the general feel of the interface. Again, I haven’t poked around much, but I like the changes for the most part. Now for the bad. Leopard is brand spanking new, and they changed a few things, including the X11 interface with Unix. I’m not certain, but I think this has made the SciPy Python library unable to compile, which affected some of my research work. Similarly, LaTeXiT isn’t working, which is upsetting because it’s what I use when making presentations, and at the time I was making a presentation. But these are all likely just because Leopard is a big change under the hood compared to Tiger. Overall, though, I’m pleased with the result. I’m a little impatient with the “old stuff not working” deal with Leopard, but given the Apple development community I’m sure it will all be resolved soon.  Many of the new features are subtle, and it will take me a while to figure out where it all is. Perhaps Apple will make the new features more obvious in OS X 10.6, which I hope they name Liger.