There really is no easy way to handle migration when it comes to software, but for the photographer, or person into photography, it also can be a bigger pain because it means checking file organization, metadata, adjustments to files, file formats, import options, and anything else that could cause a headache afterwards if not done properly. In the case of Lightroom, there’s plenty of sites to help through this (Lightroom Killer Tips, Lightroom forums, etc.), but the one thing I’ve learned is that if you’re dealing with a catalog, then why not use folders for importing and collections & collection sets for organization according to shoots, categories & themes. There’s enough options out there to make a person go crazy quite quickly, so why not plan it out beforehand (something I should’ve done better, in hindsight)?
With what I’ve come to expect between programs like Aperture & Lightroom, I know that the file handling is somewhat similar, with the exception that Aperture has the option to contain every photograph in its library (catalog for those using Lightroom), but Lightroom references the master files. The similarities end when you take about modules, because Aperture tends to unify it all with different viewing options & menu dialogue boxes whereas Lightroom separates it all into the modules (Library, Develop, Slideshow, Print & Web). With differences between them, the layout of the panels often depends on how you work with Lightroom…All I’m going to add to this is that Solo Mode works wonders when you’re in the develop module (something I learned from Lightroom Killer Tips).
Migration can be a pain, but once it’s all said & done, it’ll come out to your liking, if you get it right. The good thing about getting it done instead of holding off until it’s too late is that you just might be stuck with a computer that is too old for the new software and the version that can run on it isn’t sold anymore. Sometimes it takes some watching to figure out what move to make and sometimes, as in the case of Aperture being discontinued, the decision is made for you.