Let’s be frank. Aurora is expensive, and they charge for upgrades. An upgrade discount is only available on their website - not as an in-app purchase from the App Store. One of the most useful features of Aurora - being able to use it as a plug-in to Luminar and vice versa, only works with the app if purchased directly from Skylum. There are a few bugs - correction of lens distortion is anisotropic - one cannot fully correct for an extreme wide angle without either bowing of horizontal lines or pinching of vertical lines. There are no editing tools in Aurora other than cropping - one must use another editor in conjunction with it. That’s it for the negatives - everything else about this app is strongly positive and warrants 5 stars. I’ve used a lot of HDR photo apps over the past decade, some of which require multiple exposures and some of which can work with a single photo. Aurora does both. Simply drop a series of bracketed exposures on the app and it will, if selected, align all the images, remove ghosts and correct for chromatic aberration. It doesn’t do as good a job of aligning images as does Affinity Photo or Hydra, but the results are nevertheless outstanding. Tone mapping works with both single images and HDR brackets. The interface is exceptionally intuitive and not at all difficult to master. Aurora comes with a basic set of presets and a number of others are available on the website for free or for purchase. The free ones are adequate to address almost any situation and selecting the best one is often all that is needed to yield a great, realistic-appearing photo. Taking the time to learn the fuctions of the individual sliders on the right of the interface, will reward the user with outstanding results. Some common exposure and color controls are available, as well as less common controls such as HDR enhancement of fine, medium-sized and large details. A polarization slider works surprisingly like a polarizing filter would, helping to reduce glare from reflections and to enhance blue skies. One of the most useful features is a separate set of exposure and color controls for the top and bottom of the image. This works nicely, for example, to enhance a sunset sky while darkening the landscape below. The possibilities are endless. Just a word about Luminar 2018. I bought the old version on the App Store, but had to buy the web version to then get the upgrade price. Hence, I can’t review it directly because I didn’t purchase the upgrade from Apple at full price. Luminar is useful as an adjunct to Aurora if both are purchased from Skylum directly and not from the App Store, as they can be used as plug-ins for each other. This adds editing functions that otherwise would not be available in Aurora itself. However, there’s enough overlap of functions and an identical interface that one cannot help but wonder why Skylum didn’t integrate the two programs. If I could rate luminar separately, however, I would give it only three stars. For one thing, I cannot fathom why there is no provison to use a defalut workflow environment. Every single time one opens a new image, one is forced to select the interface elements they wish to use. Even if one uses one of the pre-defined workflows, this become tedious after a while. Otherwise, the interface is intuitive and useful. The erase and clone tools work exceptionally well, but there is no provision to reflect, rotate or scale a cloned section as there is in Photoshop and Affinity. Still, these tools when used in conjunction with Aurora make the combination formidable. The biggest shortcoming of Luminar, which makes it unsuitable as a general purpose photo editor, is the utter lack of selection tools. If one wants to combine two images, for example, it must be done entirely with layers and masks. There is no easy way to replace the sky in one image, for example, with the sky from another. There isn’t even a way to resize the canvas. Luminar is a great start and an excellent adjunct to Aurora, but it’s not yet ready to serve as a stand-alone photo editor. One final note - tech support is highly responsive and definitley not outsourced. In contacting tech support via e-mail or their website, one gets a quick resone from a developer - not a canned response - in 24 hours or less. This is among the best tech support of any I’ve used.