I never had a blackberry, but I'm a pretty fast typer on the iPhone.
And yes, it can do PushMail, since its got ActiveSync. You can also zoom in and out of eMails, so you wont have issues such as the text being too small to read.
You can use the iPhone browser just like a PC browser, it has the real internet, you can zoom in and out, it shows the sites just as your pc would do. The only thing that it currently cant do is display flash, but thats also not possible with a blackberry IIRC. I do not think there is ANY phone that has even comparable browsing capabilities as the iPhone has.