IMHO tablets are similar. Android is, without question, a stunning success in the phone world. As is iOS, which singlehandededly transformed the mobile phone industry. People expect the same pattern to repeat in the tablet world.
I disagree. There are several fundamental differences:
1. Phones have a specific purpose, which for most people is the ability to make phone calls, send and receive text messages and use maps. I would guess that these are the three biggest uses of smartphones (but it is only a guess).
What's more, I think these account for the majority of actual usage. Apps are of course important but they are an add-on. Some people will use their smartphones almost completely app free (seriously). People I think forget this too.
Tablets are a different beast. There is much less inbuilt and obvious functionality. Apple has a vision of what the use case for this. I don't think anyone else really does (yet).
The ecosystem then becomes far more important and it's Apple with the music, movies/TV and, to a lesser extent, books (mainly due to Kindle, which is cross-platform). Android simply doesn't have this ecosystem so the use case for Android tablets for most people is a much tougher and less obvious sell.
I just don't see Android tablets (or any non-iPad tablets for that matter) gaining serious mass market traction for years to come.