(Disclosure: I work for Google, but not on any cloud products like Docs or Drive.)
I never liked putting my data in iCloud. This is because I can’t access it from my non-Apple devices, like my Android phone and tablets, a Windows laptop if I buy one, or my Linux desktops. So I never enabled iCloud sync for mail, contacts, calendars or documents, preferring instead to use Gmail, Google Calendar, Simplenote and Google Docs and Drive.
I did enable sync for Notes and Reminders. I thought that because I can’t uninstall these apps, so as long as they’re there, they might as well sync. But I then found that that was depleting my iPhone’s battery, so I turned off sync.
Similarly, I had, for a while, enabled syncing for Photos, though I use OneDrive for syncing my photos, again on the logic that there’s no harm in doing so. Except that it again hurt battery life, so I turned that off again.
I also found that apps were storing data in iCloud Drive that I didn’t want stored there, either because I didn’t trust iCloud with certain kinds of sensitive information, or because I didn’t want to lock myself in to Apple’s walled garden.
But iCloud Drive  automatically saves  information without giving you a choice or even letting you know. It’s too seamless, which is a problem when it comes to sensitive information. If you open a new TextEdit window, type something, and wait a few seconds, that’s all it takes for it to be autosaved to iCloud Drive . You don’t even need to press Cmd-S.
This is unlike all other cloud services, which make it clear when information is being stored on their servers. When you open the Simplenote app, you know that data is going to be stored to Simplenote servers. Whereas iCloud is integrated with the OS and with first- and third-party apps. In fact, it’s too seamlessly integrated, to the extent that data ended up in iCloud without my knowledge or permission.
There’s another, related issue with autosaving to iCloud, which is that the save dialog box in Yosemite defaults to iCloud Drive. So, if you press Cmd-S, choose a name and press Enter without checking the location, your data is automatically stored to iCloud Drive .
To be clear, these are two different issues. The first is about what happens before you press Cmd-S (if you just open a new window and start typing), and the second is about what happens after you press Cmd-S (where the Save dialog box defaults to).
I would want to be informed and in fact asked before any data ends up in iCloud. Since iCloud Drive doesn’t have that level of control, I turned it off. As I said, this is both because I don’t trust iCloud with certain sensitive information, and because I don’t want to be locked in to Apple’s walled garden.
I had the same issue with Keychain sync — I had set up my Mac to sync with my Google account, and iCloud invited itself to sync my Google password iCloud, which is an absolute no-no. I trust iCloud far less than I do Google, so syncing my Google password via iCloud endangers my Google account.
So, I tried to delete the saved passwords from iCloud, and I then turned off Keychain sync from all my Apple devices. When you turn off Keychain sync on all your devices, Apple automatically deletes the saved passwords from their servers  .
I tried using SMS forwarding from the iPhone to my Mac, but it turned out that deleting unwanted SMSs on one device didn’t delete them on other devices, leaving behind a lot of clutter, so I turned that off as well.
The only iCloud service I still use is Safari sync, without Keychain. So it doesn’t sync passwords, only open tabs, browsing history, etc.
It’s interesting that I’ve had to turn off most of iCloud services for a variety of reasons: I don’t want to lock myself in to Apple’s walled garden. I don’t trust iCloud security or privacy. Or that trust is partial, and Apple doesn’t give me the tools to sync only what I choose to sync. Or they have other issues such as having a half-assed sync, such as not syncing deletes of SMSs.
That leaves things like AirPlay, which I’ve never used because I don’t have an Apple TV, and I’m not willing to spend money  to lock myself into Apple’s walled garden  .
So, it’s interesting how poorly designed and unsuitable for my needs iCloud is. And not just one or two iCloud services, but almost all of them. And all fail in various different ways: lock-in, security / privacy, or other flaws.
Apple is still a devices company in my view. The day it becomes hard to use other cloud services with Apple devices is the day I’ll stop buying Apple hardware.
 Or its predecessor, Documents & Data, which is the same thing for the purpose of this post.
 OS X has had autosave for many years, since Lion. But earlier, documents were autosaved to your local hard disc, which has no serious privacy and security implications, as compared to storing them to iCloud.
 You can turn iCloud Drive off for individual apps, but that doesn’t fix the problem, because another app can automatically autosave sensitive information to iCloud Drive without your approval or even knowledge.
 There’s a hack to make the save dialog box default to the local filesystem, but it works for only some apps.
 If you want to investigate what passwords are stored in iCloud, on your Mac, open Keychain Access, and in the left pane, select “iCloud”. Whatever is in this keychain syncs to iCloud, whereas things in the “login” keychain remain local to your device.
 It turns out that there’s a way to use iCloud Keychain to sync between your devices peer-to-peer without syncing your data to Apple’s servers, but this is so poorly communicated to users in the iCloud UI that it might as well not exist.
 If Apple bundled the Apple TV with their Macbooks, I might use it. It’s not unreasonable to suggest that Apple bundle a $69 device with a $1700 laptop, just as they bundle their charger.
 I don’t mind using things like AirDrop and AirPrint, because they don’t store your data, so there’s no concern with lock-in or security / privacy. In fact, AirPrint was one of the requirements when I bought a printer.
 It’s still good that Apple is making iCloud, for non-technical users, who wouldn’t set up sync otherwise, and wouldn’t know how to create an account with Google or OneDrive or Simplenote or Quip or other service, or know what they are. They’d not have their data synced, and when their device is stolen or lost or breaks, they lose their data. At least they can buy another Apple device and restore their data. They can choose not to buy an Apple device, but even in that case, they are no worse off than if their data wasn’t synced to iCloud in the first place.
Think of iCloud as a safe default over not syncing your data at all. A naive user is better off syncing their data to iCloud than they are not syncing it anywhere.