Here are my experiences with both phones...

iPhone - I got an iPhone 3G back in the day and I freakin' LOVED that phone! It replaced an old flip-phone that I had so just finally having a smart phone was awesome. I had the 3G for a little over two years... The problems started with iOS 4. I don't think they should have ever released it for the 3G - the phone was completely inadequate for it. Slowed WAY down and became just incredibly frustrating to use. I would try and send a text message and just start typing while the screen/keyboard was frozen. Halfway through the message, the phone would "catch up." Finally I had enough and decided to make the switch to Android - and Verizon.

Samsung Galaxy S Fascinate - I really dug the phone for the first few months that I had it. The screen was amazing and it was SO much faster than my old iPhone! Verizon and Samsung really dragged their feet on the Android 2.2 (Froyo) update, which ticked me off because when I got the phone, the Verizon rep told me the release was "imminent." Right... I wanted my mobile Flash, damn it! More on that later...

As more time went on, I put more and more apps and games on the Fascinate. And this thing started slowing WAY down. It was annoying and starting to become even less responsive than my old iPhone. I decided I needed to start fresh. I downloaded a custom ROM that automatically rooted the phone and cleared out all the Verizon bloatware. That's what I've been using for almost a year now and for the most part, it's been good. I love having the phone rooted and using the wireless tether!

But there are some problems... I would say that at least once a week, I need to completely reboot the phone because it's frozen. And I mean COMPLETELY reboot - taking the battery out and everything. It's annoying. I've also been on a call that's suddenly gone dead - I look at the screen and it says "phone.app has crashed." Um... Really? In the meantime I've gotten an iPad and it's pretty amazing how good iOS 4/5 is with enough processing power.

There are pros and cons to each, but I'll be getting an iPhone 4S in a couple weeks. My company is switching from BlackBerry since we now offer iOS apps and we'll need to demo them to potential customers. Work is paying for it so my Android phone is going bye bye. I'll miss some parts (like the wireless tether - definitely have to look into jailbreaking) but I'm looking forward to a more stable phone experience.