Jail break if you want to mess around with your "computer" in your iPhone or iPad, and if you are technically capable of supporting yourself when things go wrong, but if you just want to use your devices in a stable, safe and supported environment, do not do it,
Look captain buzzkill a.k.a TimHewitt makes a (emphasize "a" as in a ONE) very good point? if you aren't technically capable of supporting your jailbreak then you shouldn't)
How many times a week do we get a "my .? is broken, WHAT DO I DO" and we need to walk them through the simple steps of disabling tweaks or uninstalling tweaks or using safe mode.
Or telling people they DONT need to restore the first time their phone goes into safe mode.
For example, my latest pet peeve is "help I jailbroke my device and now my status bar?" I mean you can throw a banana at a google search and a flying monkey will hand deliver the proper fix for your status bar.
Imagine if you developed an app and have to support THAT SPECIFIC APP ONLY, and your app works on 1milion devices perfectly then one dude says blah blah blah won't work, yeah I'm jail broken? but I want your app to work on my UNIQUELY configured jail broken device.
It would be near impossible to determine which tweak or set of tweaks caused the issues.
Also security wise, if you aren't technically capable and you install ifile because someone told you too, then you leave you jail broken device on a table somewhere and a nefarious person explores your entire file system. Or even worse you installed openssh and someone browses your device while it's sitting in your pocket.?
Anyways? I disagree with captain buzzkill 99% of the time, however you shouldn't jaikbreak your device unless your willing to bite the bullet and fix your device yourself