For my self it is lack of communication between apps. What about you guys?
Wonderful question! Very relevant.
If you've read my posts it's likely you know that I've never "left" iOS, since I have a smartphone addiction heh! I have been using both Android & iPhones concurrently for years, since they were first released.
Recently over the last 12 months Androids advances have been so substantial, useful and fun, that I must admit that I'm now a lot happier with Android than iOS. So much so, I currently own a selection of models running 4.2 or 4.3.
They are:
1) Galaxy S4
2) HTC One
3) Nexus 4
4) Note 2
I have nothing bad to say about Apple, they simply have chosen the most lucrative path for themselves. Profits above all else has been their choice.
Conversely Samsung, Google & others have chosen innovation and advancement over worshipping the dollar. Both business plans have their strengths.
I'm not obsessed with apps since my heavy smartphone use revolves around the ability to view desktop websites via the spacious Android displays like the gorgeous 5" of my S4. Plus I largely detest mobile web views and mobile apps that capture you're data.
Evernote, Chrome, Firefox, Readability, Pocket, and many of the other apps I do need are readily available so I'm very happy with the efficiency I enjoy.
The overall size of the S4 in particular is ideal and is the most ergonomically comfortable for me. Battery life is excellent. There's nothing it lacks for all that I require from it.
The Apple lover in me, a guy who's used and enjoyed their laptops for years, would be truly happy to be able to say I like iOS best, but it's too limiting. With a readily accessible file system and the convenience of an Androids stand alone, PC like functionality, it's going to remain dominate in my work work flow for quite some time.
The consumer focused single operation based architecture of iOS is Apples weakness. Jailbroken or not.