I decided to take a look at a review of the HTC Hero on Engadget to get an idea of what innovations HTC has implemented on top of Android to improve the overall experience of using the device. This review is a bit dated, but given that the Hero is now being offered on Sprint I figured it was somewhat relevant.
I have played around with the Google Dev Phone (i.e. the HTC T-Mobile G1), and I also have experience developing a basic networking / statistics gathering application for Android OS. Similar to the Pre, once you provide your Google login information you are given access to a slew of Google services and applications including Gmail, Gchat, your Google contacts, and Google Voice.
The Android OS application development environment is based on Java which drastically decreases the complexity of designing for this platform, and in addition to providing an open distribution model (applications can be distributed via a website or through the Android Market) which would explain the influx of developers despite the small (albeit growing) number of users on this platform. Overall, I felt that the web documentation, multi-platform integration with Eclipse, and the ease of testing applications on either a real device or the emulator provides for a great developer experience.
While I did enjoy tying Google Voice with Gizmo on the G1 (to provide me with a cell network-less phone) and using native applications such as Gmail and MP3Tunes, I was not incredibly impressed with the method of multitasking on the device (relying on the pull-down menu to access running tasks and notifications) and not being able to keep websites loaded while I am using other applications. The Sense UI, however, in conjunction with the standard widgets currently available on Android, does allow for having simple functions concurrently and quickly accessible via the available 7 "screens". Having the weather, messaging, music player controls, bookmarks, and photo album access always running and available quickly is advantageous, but not having the ability to leave browser pages open prevents me from truly taking advantage of the multitasking goodness of the OS. I could see myself trying to make do with a Google Reader widget, but as soon as I started selecting links and interfacing between that site and Facebook/email/messaging, I feel I may be left a bit disappointed. It sure is nice for Android to have Flash lite, but Engadget demonstrates how slow it really is (hence why Adobe's announcement of Flash 10.1 mobile for WebOS and Android is so important). Anyhow, take a look at the Engadget demo of widgets in conjunction with the Sense Experience below.