uhmm since the MIUI4 port is built upon Maclaw's CM9 port..
it has got no camera as of now..!
but the battery problem has been solved..maclaw's CM9 has a damn good battery life now!
It was a problem of CPU deep sleep..which he fixed it in beta4 and MIUI also has upgraded to maclaw's beta4 porting the MIUI look..closest to iOS..
So battery being solved, you just gota wait for the camera fix..which would be like mostly (minimum) in 2 more beta builds..
Wait or till then enjoy MIUI without camera and good battery as well!