It certainly did a nice job blending the old familiar feel I enjoyed with some new tweaks and a fresh take on the desktop experience. Like with Unity, however, I never really took to the idea of the Cinnamon menu. Instead, I preferred to use Synapse as it saves me time and lessens needless mouse work.
One thing that bothered me about Cinnamon was the fact that my typical Compiz Fusion behavior didn't work. Instead, it seems that Cinnamon has its own desktop behavior through the Cinnamon desktop control panel. The 3D effects provided by Cinnamon are okay, however I decided pretty quickly that I needed to install the Compiz Fusion manager so I could tweak my desktop with the effects I enjoy.
Sadly, this didn't appear to be possible with Cinnamon. For whatever reason, my changes in the Compiz Fusion manager simply weren't taking effect. So, my choices for desktop behavior appear to be limited.
One of the "old school" options I missed from the old GNOME 2 days was the option of minimizing my windows from the panel. Thankfully Cinnamon allows me to do this. As a matter of fact, Cinnamon allows me to add and remove applets and other aspects of the panels with relative ease. This is something I was missing in Unity.
By the same token, Cinnamon doesn't offer me access to content lenses like Unity does. So I guess it comes down to what's important to you as the end user.
What I found fascinating with both desktops is how similar they are in select areas. Take the unified control panel, for example. In both Unity and Cinnamon, the control panel is basically the same. Everything is laid out according to function, sectioned off by Personal, Hardware and System settings.
The speed of the desktop environments also appears to be similar. Based on using both extensively on two similar PCs, they appear to offer about the same level of responsiveness.
Because both Unity and Cinnamon share a GNOME shell heritage, much of the menu setups and overall feel have a shared experience throughout the desktop. The differences are mostly how you access applications and browse around the desktop. The icons and settings generally feel very similar.
Final thoughts and recommendations
The first thing I want to point out is that both desktop environments provide a strong, reliable experience. Any differences really come down to the same things that might point us in the direction of KDE or Xfce. It's really a matter of how you want to browse around the desktop, as there's no wrong answer.
So which desktop is best for the advanced/intermediate user and which do I recommend for the beginner? I believe that Unity is the most newbie-friendly. Because there's no reliance on a familiarity with the Linux desktop for newbies, Unity offers a great place to launch from.
Now for intermediate and advanced users, there's no easy answer here. Many users in this area will rely on MATE, KDE or other alternatives. This is a user type with a much broader set of expectations.
I can suggest, however, is if you haven't tried Unity in Ubuntu 12.04, don't let past experiences color your judgment of the desktop. The latest release of Unity feels great and – despite it seeming a little "off" to those who prefer a minimalist desktop – users of richer desktops such as KDE might actually come to like what Unity has to offer.