I was looking at the same reason you were. I didn't have a clue Cakewalk had a new version coming out, I've been too busy with my new iClone 6 version. I've been with Cakewalk since Cakewalk DOS, and I always got notice of when they had a new version up until now. To be honest I was looking to upgrade by now. I use a lot of midi and audio channels and now and then a instrument would not start for a note or two randomly. I adjusted a tweaked everything, disabled when I remembered other drivers etc. Never was completely satisfied. Bought a new MB 2 weeks ago and Win7 pro to upgrade to 32GB of memory, and I still had same problem now and then. I downloaded Sonar Platinum last night and so far it's great. I'm knocking on wood. I been searching all over to see if they changed their audio engine or CPU processing method, but to no avail. Yes they added a vocal thing which I haven't figured out how to use and a new reverb which took awhile for me to find because it is only available in the Pro tools channel, but it's nothing that special to me. I'll try the new Sonar again later, but if this program stops the sometimes initial dead audio track, it's worth the price me. Then it's what I been hoping for. If my Sonar X3 Pro was working fine like your system, I would not have upgraded.      

Only you know why you should update.

Anderton 
But most people are upgrading solely for the new amp sims . Okay, not really. 

Yeah..come wipe the beverage spewage off my monitors now, pleeze....
Always a class clown, isn't there?

So obviously I'd be expected to say wonderful things about SONAR but...I finally finished the 2 hours of live recordings from CES from two different artists on three different nights, all 96/24 stuff, quite a bit of ProChannel and plug-ins for imaging and such because I was getting a feed from the FOH mixer (which as you know mixes for the audience, not a recording studio). I have to say the experience in Platinum has been exceptionally smooth. No crashes, fidgeting, weirdness, freezes...nothing except it just kinda purred along.
 
I haven't had a chance to play with a lot of the other goodies, though, and I'm kind of salivating as a read about the new reverb, the PRV improvements, AD2, etc. 
 
I do think the team's efforts to eradicate bugs is making some serious progress.

Don't bother upgrading is my advice. The hoops you have to jump through to install the damn thing ain't worth it. Believe me. Platinum itself looks like a joy but addicted drums 2 is, well, a bloody nightmare to install. If it is indeed possible to do.
 

That is the frustrating thing - everything else seemed to install ok. All except AD1 and AD2 which installs as 32bit unlicensed software. I still would like a situation where you could not install any 32 bit  software - no where on the command centre did I see any options to do that. If I missed it, then Cakewalk should be more explicit where to find it. Anyway, I am off to bed - it's 5am in the morning here in England! I'll sort out the refund later on today. Thanks for listening to my wails! :)

btw, I still think Sonar x3 is amazing!

I see 2 reasons to upgrade:
 
1.  To keep Cakewalk employees paid so they can continue to support this amazing DAW.  If nobody upgrades, and there is no corporate cash flow ... you know the story.  I got laid off, but I saw it coming and put in motion an Evil Plan.  I told them not to touch my Staple-er!!  So just think if people like me work at Cakewalk, and they got laid off, what might the world look like?  So by upgrading we are supporting the people who support us.
 
2.  The focus on this forum is going to shift to whatever DAW version is current.  I have ProAudio 7 disks lying around here somewhere in all this mess ... so maybe as an experiment I'll install that and post some questions.  I wonder how that would work.  Probably poorly.
 
That said, I don't plan on upgrading ---soon--- because I am in the middle of some things.  Once I manage to give birth and conclude this insanity, I'll upgrade.

I installed AD2 from the Command Center which just downloads and opens a PDF with instructions on how to get the AD2 packs. I don't think AD1 comes with the new Sonar line since, well, AD2 does. I still have AD1 installed from X3, this doesn't impact that at all, they are completely separate. I believe they are both 64 bit. I followed the instructions, downloaded and installed the AD installer, logged into my account (already created from AD1), entered my AD2 serial from the CC (also on my account page) and it gave me the option to start picking packs. I suppose that is a couple of steps more than it just happening automatically somehow, but honestly the instructions in the PDF are very clear and following them didn't cause me any pain at all. I really don't understand where you're getting hung up, and I hope you get it sorted, but it's really not difficult at all and not something that potential new customers should be given the impression is any kind of roadblock.