Rating on the Go
Often the most time consuming part of a photo shoot is just sorting through everything to find your best images. At our studio, we use star ratings as the basis for all our selections so I'm happy to see they have added that since the iPad version. Flags alone are not enough, and we typically only use them to reject the junk.
On an iPhone it's not really possible to judge critical focus, so you may want to save that for the desktop. The app is better suited for identifying stand out images in a series. I suspect we will primarily use it to do a first pass of editing, and will select the finals on a larger monitor.
If you were excited about Lightroom Mobile becoming your new favourite photo editing tool, you will be disappointed. It has important adjustments like white balance, exposure, shadows, highlights, cropping, etc. which use the same amazing Adobe processing engine as the desktop. It's great for correcting problems in an image, but useless for giving your image a "look".
It's worth noting that when you sync a collection to Creative Cloud, it automatically generates smart previews which is Adobe's own compressed format that include some basic raw functionality. The images can handle big adjustments much better than a standard jpg, especially in regards to white balance.
Adobe really missed out here, offering only Adobe adjustment presets and no ability to use your own. Maybe it's because the rendering engine on the phone can't work with all the same parameters as on the desktop, but it means that images will still need another app to give photos a colour treatment before they go live. If they could give us access to all VSCO and Mastin Labs presets from home, we could get a lot more done from within the app.
The Lightroom mobile app is very strong for version one. Image syncing with Creative Cloud works seamlessly, and their "only the basics" approach is great for getting a few important tasks done. It did lock up on me briefly a few times, but I'm confident that is just a kink to be worked out. I've heard that it can be painfully slow on some phones, so if you have anything older than an iPhone 5 it may not be for you.
It should not be thought of as a photo filter app, but a powerful link to your desktop catalog, and a sign from Adobe that they understand what is important in a professional workflow.