The restrictions feature of iOS 5 are pretty weak. Here's what's wrong and what someone needs to do to fix it.
You can do lots of restricting, in theory, and that's cool. But it's targeted at one specific user group: the kid whose parents control their iPhone / iPad / iPod. You can turn on the restrictions, and they (presumably) are enforced. For example, when I turn on restrictions to prevent any content except content rated '9+' (i.e., aimed at kids as young as 9), a bunch of my apps disappear. Cool. It has a bunch of shortcomings, though, to the point that I don't actually use it.
- You can't toggle the restrictions. That is, if you disable them, it forgets how they were set. To enable them, you have to go through all the different options and set them the way you want them all over again. I want to set up the restrictions, hand the device to my kids, take it back, and undo the restrictions. If I plan to give them the device again, I'll re-enable the restrictions. But that requires me to reset each and every setting all over again.
- You can't restrict individual apps. I can't turn off Mail, for example. I can prevent changes to the account, but I can't disable access to it entirely. You can't create a group of apps and restrict access to them by a name / group / genre, etc.
- The only way to restrict TV shows / Movies (aside from not putting them on the device to begin with) is via a ratings system. However, I put a lot of homemade content on my devices. Some are my (legally owned) ripped DVDs. Others are original movies I've made, but they have content I'd rather not expose my kids to. I can't find a way to tag a movie that I made with a content rating so that iOS will restrict it. (You can do this, according to MacOSXHints, using another app)
- There are some surprising things you can't restrict:
- SMS. Think of all the "text SUCKA to 23422 to donate £2 to goodness-knows-what" billboards around. There's no way to turn it off. With the advent of iMessage (which at the moment doesn't have the chargeable SMS feature), it would be awesome to restrict messaging to only the free iMessages.
- Phone. Again, think premium phone calling, international calling, calls over the plan's allowance, etc. Wouldn't it be great if you knew that the plan had 200 minutes and you could put a 200 minute restriction in the handset itself? Funny nobody has done this yet. With all the parents of teenagers who pay exorbitant bills, you'd think someone would have pushed this through. And then I'd put a list of always-OK numbers (so you can always reach mom & dad).
- Web settings. One good way to stop kids from visiting naughty sites on their phone is the same thing that corporations do: force all web traffic to go via a proxy. There are numerous net nanny services out there that will do that. But if you can't stop someone from changing the web settings, it is trivial to bypass those restrictions.
- Data / Data roaming. This is another chargeable feature. There is no way to limit 3G data usage. E.g., disallow it or put a handset-imposed limit on it. You also can't stop the handset user from switching on data roaming. Here in Europe, you don't have to go far to go from one country to another and suddenly start racking up international data roaming charges. And just ask people who live in New York or other northeastern US states about roaming charges from going to Canada.
Of course some of the things I mentioned can be restricted by calling up your phone carrier. You can disable SMS entirely, you can turn off data roaming, you can put content blocks on the internet connection, and you can disable access to paid / premium phone numbers. However, that's only effective for the same use case as the rest of these restrictions: when you want to turn it on, and pretty much leave it alone most of the time.
If you want to disable some features, hand it to someone else, and then take it back, this doesn't work for you. If you want to have the handset support you in keeping charges down (e.g., phone, text, internet), it won't.