I have data that I need to organize, and the easiest way to do it would be with CoreData. I also want to sync this data to Dropbox so that it will be synced across multiple iOS devices and Macs. I looked at this post, and now I am kind of concerned:
You want to look at this pessimistic take on cloud sync: Why Cloud Sync Will Never Work. It covers a lot of the issues that you are wrestling with. Many of them are largely intractable.
It is very, very, very difficult to synchronize information period. Adding in different devices, different operating systems, different data structures, etc snowballs the complexity often fatally. People have been working on variants of this problem since the 70s and things really haven't improve much.
I am especially concerned because I am pretty new to iOS and programming in general, and I was hoping it would be easier. I was wondering if anyone had some tips/tutorials/experience with doing this. I could use property lists (or a different method) to store the data, but that would make it harder later in case I wanted to change any of the attribues for the data I am storing. Is this really as complicated as they are making it sound, and should I just try to find some other way to sync the data (e.g. email, drag and drop in iTunes, etc.)?
I don't have any experience with cloud sync, but I do have experience with data management. Plist files are not at all bad in terms of data manipulation. The main problem with plist files is speed when handling large amounts of data, but for what you are intending to do they should work fine. It is difficult to provide more of an answer because in your question you did not say what kind of data, or how much data, or how often this data will be changed/accessed. If you are a beginner in iPhone development of programming in general, I will just say that Core Data has a very steep learning curve. When i first started programming for the iPhone all I used were plist's because they are simple and versatile.
Also, from reading the article that was linked in your question, it seems that he was condemning cloud providers for the way they handle data storage, and the services offered to the users. That article was written in 2009, since then great strides in "cloud" storage and syncing have been made. Also, you are not actually creating a cloud sync service, you are simply using one that is already in existence, so almost none of those problems apply to you.