Comparison between SIO2 1.4 and Unity3D iPhone 1.7 Basic --> 2010

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SIO2 1.4:
PROS: -Totally focused on programming, are you a C/C++ programmer? then you would love to make your functions and work with this engine.
-The workflow is based on blender, so you need to create your scene/models with blender or export to it, and then export the scene into the sio2 format. 
-You can access physics, sounds and some other things with this engine.
-You can do whatever game with sio2 and thanks to the C core you can add your own functions to access iphone capabilities like the ipod player, the camera or any other specific capabilites. Of course you need to program this yourself, either using obj-c or C/C++.
-All the sio2 functions are really easy to understand and the sio2animation is really powerful to have access to animated models without waste a lot of performance.
-The exporter from blender allows you to choose between gl_triangles or gl_triangle_strip, this is really important for the iphone.
-The tutorials will get you through the point in no time.

CONS:-The 2D part is really crappy, just like unity, one 2d texture means 1 draw call, also the access to 2d widgets is not very intuitive. 
-Don't support 16 bits textures or PVRTC textures.
-The audio is handled by openAL, this means you have no control over phone calls, or ipod library, so your game will ignore those 2 things and if you receive a phone call your game will loose the music until you exit the game and load it again.
-The physics are really heavy, you need to do your best to optimise the scene and try to avoid the physics as much as you can to get acceptable framerates.




Unity 1.7
PROS: -The assets pipeline is really awesome, you can use any 3d software out there, the engine support both 16bits textures and PVRTC.
-If you are an artist or a flash developer you will find the scripts system really easier.
-All the system is well integrated, apply physics, sounds or particles is really easy with only a few clicks.
-Thanks to the script system, there's a lot of premade functions available for free, (A*, object pools, cameras) just add it to your project and don't waste your time creating behaviours
-The tutorials are really advanced and will show you how to work with this engine.
-The dynamic batcher is awesome, all your models below 300 verts will be joined together to save drawcalls
-The occlusion rendering is really a boost for certain projects, you can get really detailed scenes with this technique.

CONS: -2 lenguages to choose, C# or Unityscript
-You can't disable the triangle strip option, your scene or models will have the double of polycount due this crap. Thanks unity team for allow us to loose a lot of polycount
-You can't access to outside functions, either iphone or your own libraries to handle XX behaviours
-Some bugs like the textures aren't released with the destroy() (or whatever is called) function, after 1 year the bug is still present 

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Fuente: http://eskemagames.blogspot.com.es/2010/08/comparison-between-sio2-14-and-unity3d.html