I wasn't fussed on it until I realised how locked down and restricted iOS is, would you believe me if I told you that uploading directly from browser is not at all possible when you're on an iPod/iPad/iPhone. That means you must offer another solution for users who're suffering a crippled internet experience with iOS.
I was one of those where before I used Tapatalk or ForumRunner I didn't understand or really had no interest in it. Since starting to use a mobile device(mainly my smartphone) and setting up Tapatalk and ForumRunner it makes an amazing difference in accessing the site and finding information, reading threads, moderating and pm'ing that would take forever even with the latest browser tech on the new smartphones.
If you want to fumble around with the phones built in browser go right ahead. I can make 10 posts and attachments on half of those posts in the time it would take me to do it with the phone browser. I would imagine a tablet would make it a little easier but I don't have one of those and don't know if I will ever get one. Although after having Android ICS on my Nexus I think a tablet with it would be sweet.