Thank you for your response Mister the CTO
Now I understand I suppose , but in case BlockTrail goes down for one reason or another how are we supposed to get our bitcoins back if one of the private keys is stored on your servers as you are saying since it's Multi signature wallet ? Because I'am not sure what each of the
Encrypted Primary Seed ,
Backup Seed ,
Encrypted Recovery Seed are used for because I don't see any settings to be able to import them .
However at the end of the PDF file I see that we should use your SDK and I think this is one bad thing , isn't ? I mean for people who don't have knowledge in programming it would be little bit hard to do honestly .
Also not to make Blockchain.info looks like bad or anything but could you please tell me what should make me switch from their wallet to your wallet .
Also at the end , you said there is somethings that have more priority on the meantime , could we know what are those things and could we expect updates soon ?
I've already answered your question on the other thread about the private keys:
https://bitcointalksearch.org/topic/m.12426557Also to answer your question about switching from blockchain.info, i'll try to be as objective as possible.
The features:on the mobile app we believe we have created a very user friendly interface that we hope should allow anybody to start using bitcoin. We have some nice features that blockchain.info lack, such as the ability to send to contacts in your phone without having to ever request an address from that user (one is generate automatically for their wallet). We also use the names and profile pictures of your contacts so you can easily see who a transaction was sent to or received from.
Another nice feature is on the transaction display. You can see what the value of the transaction was at the time it was sent, and compare it to the value now to see how much it has grown/decreased in value in your local currency.
The wallet also supports bitcoin URIs, so if you click on a bitcoin hyperlink it will launch the app automatically and fill in the address and amount on the send screen. We also have dynamic fees integrated, so when someone decides to do a stress test on the network your transaction will still have a higher chance of getting into the next block.
What else....we're multi-platform ( iOS, android and web browser...like bc.info), have a qr scanner in the app, generate new addresses automatically whenever you go to the receive screen (which you can copy, email or sms to someone). Oh and you can specify the amount to receive and the generated QR code will include this.
And now the technical aspectsFirstly bc.info is not an HD (hierarchical deterministic) wallet. So for every address you generate, you need to backup the private key separately. If you ever lose one of those backups you have no way to recover the funds held in that address. You also end up with an insane amount of backups (as you should not be reusing addresses, and generating a new one every time you receive funds). With our HD wallet you can create a near infinite amount of addresses and only ever need a single backup of a master private key.
Another advantage to using HD wallets is that we are able to generate new receiving addresses for a wallet without even needing their private keys. This allows you to never have to reuse addresses (which is bad for both parties' privacy) and still be able to send to someone without needing them to manually generate an address and send it to you.
Then there is the fact that we're using multi-signature technology, 2-of-3 to be specific. There are a lot of security advantages to multisig and features that we'll be able to add (such as spending limits, kill switches, address whitelists, etc) that will help you have greater control over your bitcoins and security against theft and hackers. It also means that you can use blocktrail as a service without ever having to give us access to or control over your bitcoins, and if anything were to ever happen to blocktrail you'd still be able to access your bitcoins and send them to another wallet. This includes if we get hacked. The hackers wont have enough information to do anything to your wallet, unlike with bc.info in which case they have an encrypted private key which they could brute-force attempt, rainbow table or use some other method to crack and then empty the funds in your address.
right now though we are working on ironing a few more bugs that have popped up. Thanks Omega 
