Yep, I've got a clip on tuner, and looked at Zoom recorders. I came to the conclusion I don't actually want to do much recording, these days, so I didn't bother. But there's always the odd moment, and I've been glad of it. I don't want to carry a camera round, or take loads of photos, but for the odd moment – "ooh I wish I had a camera… ah look, actually I have, I've got one on the phone" – it's great.
Like I say, the iRealBook (now called iRealB) was the prime reason. The tuner I downloaded because it was free, and good to have as a backup. And like the recorder/Camera thing, if it's on your phone, you've always got it with you.
I think I might get a tablet one day. Having a nice big screen is a very appealing idea with my deteriorating eyesight, and for more advanced stuff I think the additional capacity would be better. If I were going to do serious projects, and I could spare the money, I'd seriously consider a tablet. For now, I can't really justify the expense, and to be quite honest, the phone's more than adequate for everything I want for now.
For sheer portable convenience, and my predominantly casual use – sessions and small gigs -, the phone's the business.
If I'm away from home for instance, and have got a guitar/mandolin and my phone I really don't need anything else. I can learn new tunes, do a bit of improvising, I can find a local session on the internet, check it's still happening using the phone/text message, navigate my way to it using the sat nav, check my tuning using the tuner, perhaps record a tune set I don't know using the recorder, take a souvenir photo of the place, and if I want, upload it to facebook. If it's an 'open mic' or anything requiring 'plugging in' I can use it as a pre-amp to go directly into the PA. I can read the latest news from the BBC, (or any number of other sources) access Youtube, book trains, (or even flights) order pizzas, read a Sherlock Holmes story, play Scrabble with someone in Hawaii, find directions to local places, and listen to any music I wish to. I can also browse the Mudcat Cafe on it! And it's all on the one gadget.
Because it's my phone and about the size of a cig packet (and half the thickness) it's automatically in my pocket, and it's all easy.
Any modern smartphone is going to have pretty much this level of usefulness, but yeah, as I say, my initial reason for an iPhone was because I wanted ONE particular program, and it was music related. To some people this might seem like buying a car because you like the stereo, but for me it was reason enough at the time.