(please note that my post is meant to give others another use-case for the Vesper app, and isn't an ad for a competitor product!)
I don't care much for a diary or travel book, but I do use DayOne (for OS X and iOS) as a journal of interesting stuff I find (mostly on HN). Years ago I used delicious to save/tag webpages, after its stagnation I used other services (I don't even remember their names), then started tagging stuff in Evernote, but none of them were as natural and easy-to-use as DayOne. It lacks a lot of features, but the Markdown format and its general ease of use makes up for that - I just press Control-Shift-D and start typing (or pasting a URL + it's HN discussion link for future reference). Occasionally I write down an interesting quote or image, or a passage I've read in an article. Also, the way it stores entries is using plist files, so I'm not afraid of platform lock-in. If I find something better (like this Vesper app here), I'll just write a convertor and translate those .plist files to the new format.
I haven't tried Vesper yet (probably will wait until there's an OS X client, which is where I use DayOne 99% of the time), but it looks very nice and promising.
It's main selling point is that it encrypts all your data (notes, pictures) with SHA-256 before storing it on your device. Give it a try (Disclosure - i am the developer in the team that published this app)
A ‘Vesper’ is a cocktail drink that was introduced in Ian Fleming’s novel ‘Casino Royale’. John Gruber is a fan of the James Bond stories and of high alcoholic beverages. I don’t see how the name has anything to do with note-taking, though.
Vesper is a simple and elegant tool for collecting notes, ideas, things to do — anything you want to remember. Use tags to group related items into playlist-like collections. Vesper imposes no system; organize and curate your notes whatever way comes naturally to you. Eschewing complications, Vesper's focus is on how it feels to use it.
• Attach photos to notes.
• Use drag-and-drop to reorder items. Move important ones up, inessential ones down.
• When you’re done with an item, swipe it to send it into the archive. Out of sight, but remembered forever.
Which is presumably where Ian Fleming got the name for Vesper Lynd, the love interest in Casino Royale, for whom the drink (a martini with gin & vodka [usually an either/or thing with a martini] and lillet insted of vermouth) is named.
The MacStories Review  has a gif that shows how the app transitions from screen to screen. To me, that's the most interesting part of the app because it introduces a new UI/UX that feels faster and seems unique. Who knows if this will catch on, but it could be something not unlike pull-to-refresh, the hamburger button, or the basement metaphor on iOS if people really like it.
So maybe it's just another note app that won't work for those of us already using a different solution. But the UI/UX design is pretty cool and potentially noteworthy.
I know the original comment was deleted but I wanted to comment on this anyway since I spent the last school year teaching in a low-income high school.
First off, don't assume that the two are mutually exclusive. One of the things you learn as an educator in a tough environment is that you need hobbies as an outlet to survive and not become depressed. If you do start to go down that rabbit hole of depression you can have a poor outlook on your and your student's ability to succeed and that is not what an ideal educator needs in order to be successful in the classroom.
Second, I could have used this app over the last year to make me a better teacher. The ability to capture thoughts with words and pictures like this app provides would have been phenomenal for my organization and let me be more effective. I tried other apps and they would not have been as useful as this one would have been so don't discount it because the time was spent working on it instead of other problems that you feel are more deserving of attention.
Given the team that made it (i.e. John Gruber, Brent Simmons, Dave Wiskus), I probably wouldn't expect one any time soon. Not merely referring to their personal preferences, with only one developer on their team I can't imagine they have much resources to go cross-platform.
I thought about making an app like this for a long time. Kind of like indexing your thoughts. However, I feel like evernote may have taken the space in a way that wouldn't allow any competing apps to scale.