I have done exactly what you are thinking about doing. I went from Iphone (3G) to HTC Desire S.
There were several reasons I decided to make the move over. Firstly, I would have liked an Iphone 4, but I have to stick with o2, because my credit rating is scuppered, and o2 like me, and let me upgrade and have a contract with them. So. My options were, upgrade to the phone you are looking at moving from, upgrade to the Iphone 4, which is RIDICULOUSLY overpriced, AND they insist on you paying insurance on top of the already inflated contract rates, and unless you take out a top whack bells and whistles contract you have to hand over a tonne of cash just to get the handset.
Initially, I was going to hold fire with upgrading and see if a newer Iphone came out in a couple of months. Thats pretty much what happened with my 3G one. The 3GS arrived about 3 months later. I was slightly perturbed, but the novelty of the Iphone was enough to make me not care too much. However, even if something new did come out and usurp the 4, the 4 wasnt suddenly going to get massively cheaper.
Then my brother mentioned that there was a new HTC coming out soon, the Desire S. So I looked it up, found that the contract was not only significantly cheaper than the old one, but the handset was free. I read some reviews on it, and then decided to go ahead. Then when I ordered it, I realised that it was actually being released next day, and as o2 are really quick at upgrading, if I was lucky, I would get it on release day. Now, this sort of thing wouldnt normally bother me, but my brother is a gadget freak, and he HAS to have things the day they come out if he can. Which is why he was in the queue outside the apple store when the Ipad 2 was released for about 8 hours. With my mother, and camping chairs. And a flask.
Anyway, I am digressing. So I ordered it. And its great. I am really really happy with it. It comes with an 8gb micro sd card, you can get an app that lets you transfer your itunes playlists onto the phone so you dont have to be tied into itunes as a player, there are swathes and swathes of free apps, and Amazon MP3 Marketplace is, on the whole, significantly cheaper than Itunes for music.
Internet browsing is great, although the keyboard layout does take a little bit of practice to get the hang of when typing. Browser is VERY fast, and over wireless far outperforms my old iphone in terms of page loading speeds and download rates. Screen is clear and sharp, and android phones let you play Flash content, which is something Apple point blank refuse to implement, which frankly, is a pain in the pantaloons when it comes to bobbing around the internet sea.
One thing you do need to be a bit careful about with android is that their marketplace is open to anyone who can make an app - and they dont tend to monitor whos putting what up anywhere near as closely as Apple do. Which in turn means it would be perfectly possible for someone to lash a virus into an app, send it out for people to download for free, and make a right old mess. However, there is plenty of choice in anti-virus protection - I use AVG free, which checks everything I download as it comes in and tells me if its clean or not.
The other thing to be careful of, is the button on the top of the phone that switches on and off. Its quite delicate, and when mine got dropped a short distance but caught the edge of a flagstone right on the button, the button stopped working altogether. So if you are going to go ahead and switch, make sure and get a rubberised case for it. It only cost me £20 to get it fixed again, but a fiver on a rubberised case in the first place would have saved me having to get it fixed at all.
The only other thing to be aware of is that as you can run multiple things on it at once, you can be inadvertently chewing big chunks out of your battery life by doing so. There is no chance of you not having to charge this phone at least daily. I have been known on a heavy use day to need to do it twice. When I broke that button, I had to pretty much keep it permanently on charge, because the phone goes into sleep mode if you dont touch it for a while, and when it went into sleep mode, I didnt have a working button to re-energise it with. I couldnt just leave the screen permanently on, because I would have got screen burn, so I downloaded a live wallpaper screensaver, and that stopped it ever going properly into sleep mode, but it did chew through battery all the time.
I am very happy with it. I cant say it holds quite the same novelty value as the iphone did, but it can more than hold its own in comparison - and has a lot of actual advantages, not the least, the costs involved in being an Iphone owner.
Hope that helps.
