Comment by yojimbo311

Without describing what phones/operating systems you're expecting to target it's difficult to get specific. You will absolutely run into rendering issues between different mobile browsers, this will likely never go away, but the good news is the majority of the more recent mobile browsers are based off of, or will be, WebKit. If you go the Mobile Web application route and don't limit your scope to more recent phone OSes you're going to have to deal with the challenges of cross-browser development which could involve just as much time and effort as going a native application route with a helper framework like PhoneGap.