It wasn't too bad when you could buy Lightroom outright. I am currently on $9 per month with Photoshop but that is likely to change, and as I already owned Photoshop comparatively expensive.
You still can buy it outright, Bob. But cost shouldn't be a factor - maybe Apple are having
to price low? Aperture's cost is artificially reduced because there's not been a proper upgrade, while LR's rental cost includes an elephant too. They're both astonishing value for money.
The interface in Aperture was designed by real people. Lightroom, even though it was copied from Aperture, is cumbersome. For instance, if you are in the Library in Aperture, you see the Library but don't fill up your screen with tools you aren't using.
Apple-eyed there! Don't forget Aperture copied large elements of its design directly from Extensis Portfolio (take a look at where Apple got Aperture's product manager and lead designers). Lightroom was unveiled a month or two after Aperture, which is a bit fast for Adobe's coders to have copied it, and Lightroom had been in development as "Shadowland" at the same time as Aperture. Aperture did have a big role though - its initial welcome being so positive that it convinced Adobe that there was a market for this kind of product.
Lightroom's UI is distinctive, a series of task-oriented workspaces, while Aperture's encourages you to do one thing when you were intending to do something else. So one's good for those who focus on a task, the other for people with shorter attention spans? Not really, the UIs are just different.
Lightroom does have Lens correction and camera profiles, which Aperture does not. However the Aperture library can be put on a server along with the files, so the same catalogue can be used by multiple computers and backed up by Time Machine overnight. That is a big plus for me. Also the export to books etc is much better on Aperture. You can also use an Aperture library with iPhoto is you choose to.
Books and certainly the Slideshow are better in Aperture. Shame one can't say the same about Print, or about adjusting multiple images simultaneously - Lightroom's AutoSync mode is even better in LR5
As for using iPhoto, sure that isn't that a sign that Aperture is going to be merged into iPhoto?
The hidden secret with Apple of course is how it all goes together. I can share my Apple library to my iPhone or iPad and take it with me or play it through Apple TV for presentations and that is pretty good.
Or how it goes together as long as you stay in an Apple-only world? Aperture doesn't even work if you want to use a different brand of computer.
Unfortunately Apple seems to have abandoned Aperture at Version 3.5 and there have been no updates for a while. Keeping my files as referenced means that the same originals can be used by Aperture, Lightroom and Capture One, so I am free to use whatever. However if I leave Aperture it will be to Capture One not Lightroom.
It's amusing that the most-visited page on my Lightroom site is consistently the how-to page on Moving from Aperture to Lightroom