I actually asked this same question to their support team and was told full iOS 8 compatibility is coming later this year. No hard timelines yet though.
I just got the 3.0 update on my phone and connected it to my Firefox account. Unfortunately, after the initial sync completes the app goes into a constant crash loop, making it unusable.
This is on an iPhone 5S running iOS 8.1.1, with about 200 bookmarks. If there are any crash logs I can provide, let me know.
I hold Atul and Kiran Jonnalagada as the key reasons why I eventually gave up on my Accountancy degree and took the plunge into learning about programming & technology. Reading their articles in PCQuest and CHIP about the "magic" of technology, about the joys (and challenges) of working with FOSS/Linux and other such topics was something so alien to the grinding frustration of being a Chartered Accountant that eventually I just had to find out for myself whether it was all true.
I'm now completing a decade working in Technology and I honestly cannot see myself doing anything else.
I was lucky enough to meet Kiran a few years back and thank him (maybe not strongly enough) for helping me find my calling. I had hoped to eventually meet Atul and thank him as well - that I will never get the chance to so I will regret for the rest of my life. R.I.P Atul - "I see that I hold a sanctuary in their hearts, and in the hearts of their descendants, generations hence. It is a far, far better thing that I do, than I have ever done. It is a far, far better rest that I go to than I have ever known." ('A Tale of Two Cities')
Disclaimer: Haven't tried it out myself.