It's very difficult to get webviews to be as performant and "right feeling" as native.

That said, I think the case is very overstated, and that majority of users (i.e., not 20-somethings from Silicon Valley) won't notice or care if your app has some rough edges.

I've been working on a mobile webapp, and I'm happy with the trade offs - it's cross-platform, and it's "good enough".

Because you're going to be implementing the UI twice anyway unless you generate a completely custom one that sits between platforms. As an example, look at the linked article - can you imagine an average iDevice user instinctively knowing how to interact with that UI? There's probably nothing wrong with it per-se, but you've instantly alienated a significant non-technical audience by going off-piste with your cross-platform design.

I'm an iOS dev. A few reasons:

1. Payscale for native development is higher 2. Your product will look infinitely better. It can do more things that Phonegap can't. 3. Supporting future devices using Phonegap will be difficult. Apple TV SDK? What about the watch thing that could also come out? 4. Xcode is great.