I have been using my T-Mobile Dash for the last couple of months and really do enjoy using the device, but before I was using the Dash the Nokia E61 replaced my Treo 650. After discovering that some new VoIP applications worked on the E61, there was a new QuickOffice Suite for the S60 platform, and my Twitter usage has increased I decided to give my E61 another shot. I actually put the cool purple Nokia N95 theme on it too and love the looks of it. Fring lets me call people via WiFi on Skype, Google Talk, and MSN Messenger or even chat with them using these clients and this is just too cool. The more I play with the E61, the more I think an E61i with the camera may be in my future since a camera is really the only thing I miss from the E61.
Compared to the Dash, I love the way you can customize the folders, main Home screen, and look and feel of these S60 devices. I do like the way Windows Mobile Smartphones use the smart dialing feature though and this is missed on S60 devices. The web browsing on the E61 is incredible though and the BEST of any mobile device. The new free Nokia Maps application is also awesome since you get GPS navigation and maps for free.
I wish there was a PocketBible client for S60, but understand it can be difficult to develop and support the S60 platform with an application and books like this since Nokia makes regular updates to the OS that break the functionality on previous versions. There are some decent Bible applications for S60 though so that helps in a pinch.