The HTC Butterfly S runs Android 4.2.2 with Sense 5, which is right on par with the latest offerings from HTC, the One and One mini. The software includes the exclusive BlinkFeed and Zoe features. Here's a quick showcase of the HTC Butterfly S hardware and software.
HTC Sense goes against the grain of most Android custom launchers and relies heavily on vertical scrolling, which can take some getting used to if you're coming from a different brand.
BlinkFeed is the first place you'd encounter it - it's a stream of articles from around the web (HTC has partnered with some 10,000 providers) combined with account updates from SNS like Facebook and Twitter.
BlinkFeed is a part of the homescreen - the leftmost pane. When you tap on an item you get a preview with one big picture and a short blurb. Social networking items open the respective app instead. You can also search BlinkFeed and post updates to social networks straight from there.
Note that BlinkFeed needs a data connection to update, but you can set it to update over Wi-Fi only.
Moving to the right of BlinkFeed you'll find the series of standard homescreen panes.
A long press on the homescreen or a pinch gesture trigger edit mode. You can add and remove homescreen panes, rearrange existing ones and set one of them as Home (the one the Home buttons will always bring you to). The only limitation is that you can't remove or relocate the BlinkFeed, which is always the leftmost pane.
You can pull out widgets, app shortcuts and other shortcuts (e.g. one that links to a specific Dropbox folder, a Gmail label, a setting and so on). You switch between these via a dropdown menu, not really the standard Android way. If you prefer, you can pull out app shortcuts from the app drawer too - you have to drag a shortcut to the "Shortcut" area that shows up in the top left and then drop it somewhere on the homescreen.
The app drawer is the second place where HTC went with vertical scrolling instead of the more popular paged interface. The drawer displays a 3 x 4 grip of shortcuts by default (which leaves a lot of padding around icons). You can use folders to group similar apps and make better use of the screen space. The other option is to switch to a 4 x 5 grid in the settings menu.
Note that to access the settings in the app drawer and BlinkFeed you have to swipe down. The Butterfly S doesn't have a Menu button, but you can assign the long press action of the Home button to cover for it. If you do that, you'll give up its default purpose of opening Google Now - which will be a swipe up gesture instead.
At the top of the app drawer is a big clock with date and weather info (a big icon and smaller text with more details). This same clock is at the top of the BlinkFeed screen, which makes the two feel very similar.
The shortcut dock at the bottom holds four shortcuts plus the app drawer button in the middle. These icons are always visible - in BlinkFeed, in the regular screens, in the app drawer, even on the lockscreen.
The notification area is pretty much stock android - it shows only notifications by default (below the top row, which is reserved for the time and date, plus two shortcuts). As of Android 4.2.2, Sense 5 also has toggles in the notification area.
Another novelty courtesy of Android 4.2.2 is the widget lockscreen. It's disabled by default, you have to toggle it on from the Personalize menu. Unlike the stock variety, you only get to pick a single widget, there are no multiple pages.
The widget lockscreen is much like the default one with a big clock and a weather icon, along with four quick shortcuts - you drag them up and release to launch the app they link to, just like the unlocking gesture.
HTC has fiddled with the app switcher - it is now launched by double tapping the Home key (unless you set that to be launching the in-app Menu, then it's a swipe up gesture) and it shows a 3 x 3 grid of thumbnails of the recent apps. The upside is that you don't have to scroll like you do in the regular app switcher, the downside is that you can't scroll - you only get to see the last 9 apps and no more (for some that's quite enough). You can swipe up to close an app (which leaves an empty slot, an older app doesn't fill its place).
There's an interesting option in the phone's Security settings, borrowed from Windows Phone 8. It's called Kid mode and is actually an app that lets you set up a profile for each of your kids, with a photo and birthdate and pick which apps they have access to. One annoying bit is that to enable Kid mode the first time around, you need to sign up via email.
The HTC Butterfly S also comes with a dedicated Car mode screen, which has been styled to look like the rest of the interface. There are only five big controls besides the clock and weather info. There's music info too, which takes a whole row by itself, along with shortcuts to Navigation, Dialer, the Music player (again) and Voice commands.
The Sense customizations also extend to the Settings menu - HTC has prettified it a bit with custom icons and added several new options (like Media output and Personalize).
If you're upgrading from another phone, you should give the Setup app a spin. It hooks up to your old phone over Bluetooth and pulls all the data it can, even things that Google doesn't sync (settings and such, not just the contacts). This also works for phones that can't sync with Google, like various feature phones.