Yes, I use it, and I have to say, using it with CW, it is freaking amazing. One of the things that I've railed about in the past with CW/Sonar is that is has (IMO) very poor loop construction/manipulation of samples, and it's difficult to demo candidate samples 'on the fly' even within the Media Selector. The Loopcloud plugin makes this a much less tedious, and more enjoyable process. One really cool thing is that it has a Pitch knob, which is a high-quality pitch-shifter. It will allow you to pitch-shift a sample (Loopcloud or your own samples) to fit your song. Along with being able to do sample edits and apply basic effects to a sample, again on the fly. Then, when you are happy, you can drag/drop a complete sample with all the edits applied.
The way I use it is that I create a Instrument track with it, then start the Loopcloud application. I then setup a loop in my song where I would like to have a new sample, and then use the Loopcloud application to select one. I can change the time, pitch, starting/ending time, apply effects, cut/paste samples all on the fly. As mentioned above, it gives more of an Ableton-loop construction feel to your workflow. It is my hope that the Bakers would develop something like this for CW, they could even setup a sample purchasing thing similar to Loopcloud.
I have Splice as well, and I like Splice, mainly because of their gigantic sample library, but man, it's a pain to demo their samples in that web interface. I end up having to download them from Splice and bring them into my Loopcloud Library to use them.
As Aidan mentioned, it's a great inspiration boost. If you try it and end up liking it, if you can wait (or just pay the monthly until then), they had 1/2 price on the Annual subscription around Black Friday/holidays, and I would think they will have such a sale again. I think it was like $60.00. Out of all the stuff I bought during the holidays, this has been the most used and enjoyed of them all, and I just thought it would be a throw-away thing that I could just get $60.00 of quality loops from.
Just wanted to share my positive experience with it.