As an IT Director and a new Android user since November (when the Motorola Droid arrived), it was critical for me to have a solid application for accessing my office e-mail, calendar and contacts. Android 2.1's native support for Exchange Active Sync is very basic. It get's the job done in a minimalist fashion. But if you want something better, Touchdown is the way to go. I tried several apps from the Android market before settling on Touchdown.
If you have Microsoft Exchange 2003 SP2 or higher, Touchdown should work for you. It supports SSL for connection security and it also supports remote wipe and PIN enforcement (for those IT departments that require it). Those last two features are expected in Android 2.2 (Froyo) but the older versions of Android do not support remote wipe or PIN enforcement, which has left many Android users in a lurch because many companies require that a device support remote wipe and PIN enforcement.
A few of my favorite features of Touchdown include:
* You can display e-mails in their HTML format (unlike the native app in Android).
* You can easily customize the notifications for new messages and appointment reminders, which includes choosing unique sounds and colors for the flashing led.
* You can search and access the main Exchange address book (GAL) for your company. The native Android app cannot.
* You can easily select which folders to have synchronized, and you can designate the initial email download size limit that best suits your needs, so that large messages aren't automatically (fully) download, which would thus eat up battery life and/or storage capacity.
* You can search and/or filter your messages easily.
* Touchdown offers 'Search as you type' functionality when addressing messages.
* Touchdown offers plenty of optional settings that the user can configure so that the app works to their liking.
Support from Nitrodesk has also been quite good. I have contacted the author several times since purchasing the app in November, and he's been very responsive. The application has continued to improve since my purchase, and it keeps getting better and better. The latest releases have been very solid and reliable. One small issue that I will mention is that Touchdown does get a little sluggish when free memory in Android drops below 40 MB. But this is more of an Android issue than one for Touchdown.
When Android 2.2 becomes readily available, it will be nice to have native support from Android for Exchange security policies. This should in turn make Android a more accepted device in the corporate world. But for me personally, Touchdown is my most frequently used app on my Droid and I don't see anything changing that in the near future.