The EVO Shift 4G runs Android 2.2 with HTC Sense running over it. Now, this isn't the latest version of HTC Sense; we won't see that until the HTC Inspire 4G launches. Yes, the Shift 4G supports Flash, so you'll be able to watch Flash videos, view Flash-enabled pages and play Flash-based games. Hopefully, the EVO Shift 4G will be updated to Android 2.3 sooner rather than later, which should undoubtedly improve performance overall.
We've written a lot about HTC Sense in the past so I'll just quickly summarize what works and what doesn't with the overlay. Out of all of the Android overlays, Sense is the best-looking of the bunch. The latest iteration of Sense features Leap, which is essentially an elegant way of handling multitasking; it's actually a bit reminiscent of (remember WebOS?). Pinch anywhere on the homescreen, and you'll jump to seven thumbnail versions of your homescreens. From there, you can go to any of those open applications or close out of one.
Friend Stream, HTC's social network aggregator, allows you to view your friends' status updates, shared links, and pictures all in one seamless view. Supported social networks include Facebook, Flickr, Twitter, and others. I find such social network feeds a bit annoying--do I really need to see everybody's tweets and Facebook status updates all mixed up together? But I suppose if you're an avid social networker, seeing all of these updates in one place is useful.
I'm not a huge fan of HTC's Sense music player. The album art doesn't take advantage of the EVO 4G's large display while the app is in Now Playing mode; it remains thumbnail-size. The Sense player is slightly prettier than the dull-as-dirt Android player, but I prefer iTunes or Samsung's TouchWiz player. Audio sounded good, though, and the player supports a respectable range of audio and video formats.
Like other Sprint 4G phones, the Shift 4G comes with Sprint's Mobile Hotspot, which lets you connect up to eight Wi-Fi enabled devices. It also comes loaded with all the usual Sprint apps (or bloatware, depending how you look at it) as well as the suite of Google services like GTalk, Gmail, Google Navigation, YouTube, etc.