Has anyone used or demo'd this one?

I moved to Samplitude about 3 years ago. Very cool program and I think the audio side is better than Sonar (which is why I moved) with a lot of configurability. Sonar's MIDI is probably better, but Samp's onboard plugins are excellent, and the suite version comes with the 70BG version of the Independence synth. For me the learning curve wasn't bad at all. Pitch and tempo stretching are standard features. Object-based editing in Samp, as opposed to clip-based in Sonar (if that matters to you).
 
Also, there is a guy called Kraznet who has put up a ton of tutorial videos on YouTube.

 
I agree with Ruben, for the most part. I've owned Samplitude for a year, and have begun to learn it more seriously since Cakewalk's announcement. It's very powerful, and the audio side is good, and the midi side is very decent and perfectly useable (but not as good as Sonar, in my opinion).
 
It is taking me a while to get completely comfortable with it, though. I found signal routing to be less intuitive than Sonar, and I've been having issues with bouncing midi tracks, as I find that sub-system to be both inefficient and not clearly designed, and when I am using my Play libraries I run into problems with fast bounce, as Play delivers intermittent sound when fast bouncing. Trying to figure out a way to bounce in real time has been surprisingly awkward. 
 
The program is very, very mature and stable -- no bugs, no crashes, no twitches of any kind (although some folks do report a bit of instability while scanning VSTs, I have not experienced this). The GUI is kind of drab and I'm not hugely keen on the layout or the color scheme, which can sometimes make it hard to differentiate between elements on the screen. 
 
The included plugins are quite nice, the sample library is actually quite good, with lots of stuff included. The forums at Magix have people who respond and a decent amount of information. 
 
So, it's a perfectly useful DAW that will do everything you need, has a bit of a learning curve for Sonar users, and comes with lots of features and extras. I am glad I have it, and it is my backup DAW should Sonar eventually stop working.

Magix Samplitude Music Studio is a pretty cool more budget alternative for Music Creator 7, Sonar Artist, and maybe even some Sonar Professional users also.
Like someone else here, I’ve had it about a year (along with MMLive and a few others) haven’t used it much, but when I do open it up, I am always so surprised at the Magix products and what they offer differently than others.
With that said, I wish my Sonar Pro and Cakewalk was sticking around longer :-(

Way back in the day, I wrote the English user's manual for Samplitude 2496.
IMO, At that time... on the audio side, it was FAR beyond all other DAWs.
The Object Editor could do so many things... and all in realtime (per segment of audio).
 
Reaper's Item Editor was "inspired" by Samplitude's Object Editor.  
 
The MIDI side of Samplitude has matured over the years... but lacks the esoteric features you'd find in Cubase.
The Audio side of Samplitude is the best you'll find.

I bought it about a year ago during a holiday sale. Being a guitar player with G.A.S.
This is just a hobby for me and don't have a lot of time for it or experience with DAW's. With that being said it is a nice looking and deep program from my perspective.
I will second what other people have said about the audio engine, it was something about the sound, clarity, presence, Etc. I know a lot of people say that all DAW's should sound the same, that it's all 1's and 0's. But it does sound good.
The effects are nice, there is a suite of effects called the "Analog Modeling Suite" with a compressor called Ammunition that I love.
http://www.magix.com/us/analogue-modelling-suite/
 
With that being said every time I try using it I seem to end up with the program on one monitor and the pdf manual on my second monitor. And as I said I do not have a lot of time and end up going back to Mixcraft. I do tell myself every couple of weeks to give it another shot and force myself to learn more about it.
If I had more experience and time and this was more then just a hobby it would probably be my main DAW.

Not related to the sound and not a feature for most users, but that is the only DAW with the following text in the specification:

It is important to us that our products are barrier free. Visually impaired individuals, who usually have especially good hearing, should be able to use our audio products.
We have integrated new features to the latest version of Samplitude Pro X3 and Sequoia 13 to assist blind and visually impaired users in using the software to its fullest potential.

And I have heard that really works (unlike Sonar X2+).
 

Yes! My patience has paid off! Check it out, y'all!
 

telecharge
Yes! My patience has paid off! Check it out, y'all!
 

Wow, seriously! ?
That’s craxy cheap buy for its normal price!

That's an amazing price for this software. It's cheaper than I paid for an update from Pro X. Perhaps this means that Pro X4 is close to coming out.