We just went through with vbmobile on our site and finally got it implemented over the weekend. Its been a HUGE success. A lot of my members (myself included) use tapatalk and quite a few people are sick of the backwards changes and bugs, etc. Everyone who has tried it thus far loves it. Its fast, simple and streamlined. It strips away a lot of the fluff and just focuses on the forum experience. And as said above, it does allow you to build on top of it.
I would strongly recommend this if youre looking for a true mobile solution.
You can see it in action on my site via -
http://www.thechicagogarage.com/forum/?styleid=25