Is MultiBit secure? And hong long will MultiBit import .aes.json take? Two questions:


Is MultiBit secure? 
I opened a wallet in blockchain.info, and I want to import .aes.json to MultiBit, hong long will MultiBit import .aes.json take? I waited too long.
There is currently a bug in the 0.5.9 code that prevents it from loading blockchain.info wallets. It is fixed in the develop code and will get into version 0.5.10 (which will probably be released after the Bitcoin conference now). The older versions work fine - version 0.4.23 is in https://multibit.org/releases . You could just use that version for the import. 

Is MultiBit secure ?
Security for bitcoins has several aspects - here are the main ones:


Is it open source ? Yes.
Can you trust the developers ? Well that is for you to decide but I've been working on it solid for over a year now and code it 'in the open' not pseudonymously. 
Can you check the downloads are the correct ones ? This is important now that Trojans have started appearing. Yes. Download from https://multibit.org. Check the binary against the PGP signatures. The Mac version is also signed with a Mac developer cert and soon I'll start doing the same with the Windows version. Not enough? : build it directly from the code. 
Do you control the private keys ? Yes, there are stored locally. 
Can you encrypt them ? Yes. 
What about malware and keyloggers ? Until we get hardware wallets bitcoin clients in general are vulnerable to an attack by malware and keyloggers combined. You need to practice 'Safe Computing' on the computer you have your bitcoin on. If you are dealing with serious amounts of bitcoin sign your transactions offline with either Electrum or Armory rather than MultiBit.