I made some applications for iPhone with more complex geometry 8000+ poly (just for testing) and it works correct
There should be problem with your allocations in VBO (indexes probably) which should be OK for simple objects like cube in front view
- check your index count and vertex count in VBO creation state
- also check for quads vs. triangles (index count from 4 to 6), are you exporting direct triangles?

I made some applications for iPhone with more complex geometry 8000+ poly (just for testing) and it works correct
There should be problem with your allocations in VBO (indexes probably) which should be OK for simple objects like cube in front view
- check your index count and vertex count in VBO creation state
- also check for quads vs. triangles, are you exporting direct triangles?