Adobe announced the release of Lightroom for iPad, joining some of Adobe's other products like Photoshop Express and Adobe Air. However, Lightroom will function as an extension of the desktop version, rather than a standalone app.
Although the app itself is free, you will need to be a Adobe Creative Cloud subscriber to use it, along with other Adobe software. You can see some of the pricing options on Adobe's website.
Users can now use many of the same editing tools found in Lightroom without the need for a desktop. Adobe focused on desktop and mobile synchronization, so photographers can now make changes within Lightroom on iPad, which corresponds with your catalog on Mac or PC.
Using Lightroom 5's Smart Preview technology, low resolution images are displayed in lieu of original images with a larger file size. A "stand-in" for the initial image preserves the same characteristics, but is only a fraction of the original file size.
Functionally, the app loses some of the features you would find on the desktop version, but retains many of the basics. Image controls like exposure, contrast, clarity, filter, tones, and crops are all included, among other editing options.
If you opt for a Creative Cloud membership, the cheapest plan starts at $9.99 a month and includes access to Lightroom 5, Photoshop CC, Lightroom mobile and a public portfolio site through Behance. You can read more about Lightroom mobile on Adobe's blog.