I use SpeakOut's web browsing service with an unlocked Blackberry running Opera Mini as my browser. I have no problems with text entry and regularly use Yahoo and Gmail. It's not blindingly fast, but I have the option of surfing and checking email without breaking the bank.
The quality of your browsing experience will depend a lot on the browser you use. Some phones have terrible proprietary browsers and cramped screens that make the experience hell. If you can run Safari or Opera, your world will be a much happier place.