After running the calibration tool and adjusting pen sensitivity, drawing is wonderful. The screen protector has a satiny finish much better suited to the pen's hard plastic nibs than bare glass.
Edge parallax is a bit of a problem, especially in the upper left corner of the display. In Manga Studio, I found myself relying on the Display Application Menu icon located just above the New Canvas tab rather than going up to the file menu. The cursor and the pen tip are perfectly aligned just below the command bar, but at the menu bar, there's about a quarter-inch offset. I can deal with it, but it does require a pause to concentrate to target the menu items.
UPDATE 8/25/14 After working with the GT-220 for several more days, I've become more aware of the device's parallax issues. Besides the cursor drift problems I cite above, the pen display also has a significant gap between the glass and the screen. This separation is more pronounced as you view your work from an angle. In Manga Studio, there is never less than an 1/8-inch gap between the cursor and the pen tip, so inking precisely requires more concentration than I'm accustomed to on Windows tablets. Huion tells me that they're working on improving this via a driver update.
Moving on to Photoshop CC 2014, it took some Googling to learn that the software now requires a PSUserConfig.txt file entry in order to work with any Wintab tablet.
Create a text file named PSUserConfig.txt and place it in the Users/UserName/AppData/Roaming/Adobe/Adobe Photoshop CC 2014/Adobe Photoshop CC 2014 Settings. The contents of the text file should read:
# Use WinTab
I still couldn't get pen pressure to work until I discovered that Huion just published an updated driver here: http://huion-tablet.tumblr.com/post/95172457923/huion-new-driver-updated-20140818-pressure
No matter what I tried I couldn't get pressure sensitivity in Sketchbook Pro 7. This experience bodes ill for all tablet users as software migrates to RealTimeStylus or Microsoft's INK API. Device manufacturers are going to probably need to issue new drivers for older devices or software developers are going to need to come up with better backward compatibility.
I also tested with Krita Desktop and Paint Tool SAI 1.2 and both worked fine. Corel Painter 2015 recognized pen pressure, but as on other tablets I've tried (including the Surface Pro 3), some brushes have their initial activation pressure set so high many strokes are not recognized.
As of this writing I haven't tried hooking the GT-220 up to a Surface Pro. I'm reluctant to do so with the Surface Pro 3 because I have too much software on it that requires the N-Trig Wintab driver. Installing the Huion drivers will overwrite any Wintab driver on the system. So if you want to use the pen display with a tablet pc, software has to have an easy way to switch between RealTimeStylus (TabletPC) and Wintab. Very few applications handle this as elegantly as Manga Studio/Clip Studio Paint.
As I wrote at the outset, the Huion GT-220 isn't perfect and depending on your software preference may not be useable at the moment. But if you're a Manga Studio/Clip Studio Paint user, it's a great asset despite its few kinks.
I know I'll certainly be very happy with it until someone comes along with a multi-touch capable pen display, a combination only available currently in the highest end Wacom Cintiqs, the 22HD Touch and the 24HD Touch, which retail for $2499 and $2999 respectively. (For a minimum $1600 savings, I can live without mult-touch gestures.)
At the dawn of Windows 8, before I started the quest for knowledge that led to the creation of this blog, I dreamed of finding a penabled all-in-one from one of the major OEMs like Dell or HP. I still can't understand why that hasn't happened.
Perhaps it will be up to Microsoft to make this dream device. I can't help but fantasize about a 22+-inch Surface Pro all-in-one with a Huion digitizer. Now that would be real dream machine.
In the meantime, the $899 Huion Interactive IPS Pen Display GT-220 will turn any pc into the next best thing.