iPhone lives in my pocket, and gets used for most of the things the desktop does when I'm out and about. The keyboard is a bit fiddly, but my eyesight is good. It's on iOS7.0.5 jailbroken: there's some software on it that I use a lot, and that Apple doesn't approve of, so updates are "orf". I've been very tempted, several times, to replace it with something Android that doesn't have all the restrictions: I've resisted temptation so far.
The iPad gets less use unless we're away on holiday, when it does duty as desktop. The biggest pain is having about 25 App updates to do every time I use it. It's updating right now, preparatory to seeing if I can find the iOS9 update to go on it. That may have to be via iTunes and the desktop.
The Laptop is a bit of an anachronism, but as long as it works, it'll get the occasional job to do.
The desktop does the bulk of the work. It's on Windows 7HP (and staying there, for now at least, because the video card manufacturer seems to have lost the knack of writing drivers that work).
The good bit is that my diary and address book synchronise seamlessly between all of them. Some e-mail accounts do, too.
and fancy time-lapse videos of sunsets and flowers opening (added App for this) and slo-mo videos of 'things I like'. Saves having to carry a camera, but the trade off of immediacy for quality is noted. I have used the torch function when travelling, and the alarm too. I no longer wear a watch - superfluous. Have used the recording function when discussing things with police too 
