Ive had the HTC Magic (Android 1.5 & 1.6) and now have a snapdragon HTC Desire (2.1) and its fast.
The way it links things together is just seamless, my personal and corporate emails, calendars and contacts for example. To tout an Apple saying, it just works. Free Navigation which is fantastic and there are some great launchers out at the moment which really let you customize it to a way which suits you. This is what wins me over the iPhone. Well that plus the notification bar which is awesome. No matter where you are in the phone if you get a mail or message, you can deal with it. With the iPhone, you can re-arrange your icons, but thats pretty much all you can do (with regards to laying your phone out how you want). I wish I could post some screens / a video of how clean I have it running as im sure you would be impressed. Simple calendar on the right screen, 4 of my fav handy icons on the left screen, simple clock and controls on the centre (wifi, bt, sync, brightness) on / off etc. Then on the bottom I have icons for calls, people, App tray, messages, camera (which is surprisingly good actually) and this tray I can scroll left and right independantly of the home screen, so I can easily get at facebook, twitter, emails, time dock, music etc without shifting the top. That might sound messy but its really clean. Im not a lover of loads of widgets on the go personally unlike my friends but tbh I have it configured for speed and ease of use as apposed to eyecandy and striking. I just like to have it that way. Im running LauncherPro and its much, much smoother than Sense or any other launcher ive seen. It has that elasticy snappy feel to it much like the iPhone plus I can now run my home screen landscape.
The Desire totally puts to shame my old Magic but its processor is twice as fast and it has twice the RAM so I guess at the time, that's what the magic was missing. They are getting smooth now.
The other part I like is they OTA updates to you. Im expecting Froyo (2.2) any day really and now they are talking about Gingerbread (3.0?) Which they are hoping to revamp the way you use the UI as Froyo is super fast on all the benchmarks and side by side on like for like demo's I have seen.
Sure im a fan boy, i've been converted. I can hold my hands up and say that. It just does too many things (for me) that I find productive and enjoy. I've also inadvertently converted many others and all of whom are happy.
All this said I would just definitely recommend you at least check one out. Go get a HTC Desire running in your hand in a shop and play with it for a little while.
Sure it has some shortfalls, battery isnt best, screen isnt HD like the new iPhone but it has no more than any other device out there at the moment. Its TCO is a damsight less than the iPhone and its growing at an amazing rate so yeah... good times ahead for me
I used to be a Windows Mobile fan boy back in the day but it just seemed to loose steam at one point so I went Symbian... Lost it, so I wanted an iPhone but after trying Android just fell in love with it. I can honestly say this though, ive never seen something grow / move so damned fast in the mobile realm.
Best of luck with your decision!