As excited as we may be about Steam machines democratizing PC gaming in the living room, there’s no question Valve’s new platform will encounter some obstacles on its road to success. Valve will have to persuade other developers to support a new platform, for starters, and it will be forced to work with hardware makers, particularly AMD and Nvidia, to ensure SteamOS gets top-notch driver support. On top of that, Valve will need to convince PC gamers to step out of their comfort zone and embrace a wildly different operating system without support for many familiar apps and games.

At the Game Developers Conference last month, I became aware of another potential bump on the road: the Steam controller.

The Steam controller has a unique design with dual touchpads instead of analog sticks or d-pads. Its design is supposed to let gamers play not just shooters, but also titles that traditionally require a keyboard and mouse. (Think Civilization V and Diablo III.) When Valve first revealed the Steam controller, it said the device’s dual touchpads have a much higher resolution than typical analog sticks. Thanks to a “new generation of super-precise haptic feedback,” the touchpads can also convey “speed, boundaries, thresholds, textures, action confirmations, or any other events about which game designers want players to be aware.” This video shows just how fast and versatile the Stream controller can be for a seasoned user.

On paper, that all looks great. Conventional console controllers are markedly slower and less accurate than a mouse and keyboard even in first-person shooters. The Steam controller promises not just to remedy that, but also to make a whole bunch of new games comfortable to play from the couch.

But there’s a downside. As I learned first-hand, the Steam controller has a pretty steep learning curve—steep enough, I fear, to put off some potential converts.

Valve had several Steam machines set up at its GDC booth, all hooked up to the very latest Steam controller prototypes. Over a period of about 10 minutes, I gave the controller a shot in both Portal 2 and a Japanese-looking side-scroller whose name I can’t recall. In Portal 2, the Steam controller was so unlike anything I’d ever used that I was completely useless with it. Oh, the shape of the device was excellent, and the positioning of the buttons was great. But I could barely circle-strafe, and precise aiming was entirely out of the question. So was the kind of quick response needed to complete the next puzzle. All I could do was run around and try to get a feel for the elusive touchpad controls.

At this point, one of the Valve guys shepherding the demos told me I’d better not run Portal 2, since it tended to crash on the particular Steam machine I was using. So, I fired up the aforementioned side-scroller. There, the 2D environment made it easier to steer my character around, but I still had trouble with the sensitivity and response of the two touchpads. The main thing that threw me off, I think, was that the touchpads register absolute finger positions—not relative ones like the touchpad on a laptop might. Holding your thumbs in exactly the right positions with only a couple of concentric ridges for guidance is… tricky.

After getting myself killed a few times, I put down the controller and spoke with the Valve guy. Was I just uncommonly clumsy, I asked, or was the learning curve really so steep? To my surprise, he said it personally took him eight hours to get fully acquainted with the Steam controller. The learning process does vary from user to user, he added, and faster learners can apparently pull off the same feat in only 15 minutes. But based on my own experience, that probably requires some uncanny dexterity.

Even 15 minutes is a long time, though, especially for someone who’s used to instant familiarity with mice, keyboards, and conventional gamepads. A quick brush with a Steam machine at a store, a friend’s house, or some other venue might easily discourage a future purchase. If we’re looking at eight hours of learning time for a Valve employee, I worry that some folks will spend much longer wrestling with the thing. For a brand-new platform whose success will hinge on broad adoption, that’s not a good thing.

Simply plugging an Xbox controller into a Steam machine would take care of that problem. I’m sure Valve will make it possible. That said, an Xbox controller would also put players at a disadvantage in multiplayer skirmishes, where they’d likely fight PC players armed with keyboards, mice, and (yes) Steam controllers. An Xbox gamepad would also seriously limit the playability of Steam’s many point-and-click games—and one of the big selling points of Steam machines is their ability to bring those titles to the living room.

What does Valve think of all this? Well, the Valve guy I spoke to said the company is indeed concerned about the Steam controller’s steep learning curve—but it thinks the size of Steam’s current user base will work in its favor, and so will the Steam controller’s support for titles that can’t be played with conventional gamepads. In other words, it’s willing to gamble that the pros will outweigh the cons.

I suppose I can’t argue with that. Still, I can’t shake the feeling that one of the Steam machines’ hottest features may also be a barrier to their success.