I made it all the way to the "Proceed" button before I got that feeling. The feeling that I was buying into the ground floor, not buying into a great device. That's why I didn't pull the trigger and buy the phone that me and every other Android nerd have been asking for: a best-in-class piece of hardware running standard, "stock" Android. For me, a big part of it is the buttons.
Samsung and HTC have killer phones on the market right now: the Galaxy S4 and the One, respectively. Both are made by companies that want to differentiate themselves, so they run, by default, a customized "skin" and software replacements for default Android functions: the music player, the camera, the look and feel of the home screen, and so on. Some Android fans prefer the clean, minimal, standardized look of "stock" Android, and many dislike the slow feel of the custom skins. As of Wednesday, Google is giving them just what they want: https://play.google.com/store/devices?feature=home-mt-0#?t=W251bGwsMSwyLDcwMywiZGV2aWNlc19ob21lIl0, sold unlocked and at nearly full price ($600 for the One, $650 for the S4).
People who get much more into device reviewing than I do, such as JR Raphael at ComputerWorld and Kevin Tofel at GigaOM, have niggles about what the Play Editions lose from their original "skins": camera processing and tools, home screen customizations, Google Wallet, and other bits. What really would drive me nuts, though, are the buttons.
With their original phones, HTC and Samsung both made hardware choices that Google would probably not prefer: a physical home button on the S4, and a different order for the capacitive (on the hardware, touch-sensitive) buttons on the One. The standard for newer phones, as Google sees it, is "virtual buttons," or buttons that are rendered by the software. Google designed the current Android OS, 4.2.2 ("Jelly Bean"), with virtual buttons in mind, and added a few caveat options for older devices.
The S4 has a capacitive menu button. Much older phones have those, too, but mostly get by with little tweaks to Android 4.2. On the GS4 "Play Edition," however, the on-screen overflow menu option (usually three dots, turned sideways/vertical) is missing from many apps. You are somehow expected to remember to press the Menu button to see more options, and you don't get a hint that those extra options might be there.
On the One, which only has two capacitive buttons, Home and Back, apps that need a menu option just put the overflow menu on the screen. Which would be fine, if, for some reason, the version of Android on the One put that menu button in a black bar at the bottom of the app, with just the menu dots smack in the middle of the screen. It's a pretty cruddy feeling, I could imagine, having one of the newest and best phones around, yet using software that seems like it was designed for phones made three years ago.
So those buttons make me think twice, and so does the fact that we're 8 months past the last Google-pushed Nexus phone, the Nexus 4. It feels like another Nexus may be in the works, and I can probably hold out on my Galaxy Nexus until then. At the ridiculous rate at which technology writers use and discard phones, that feels something like holding out for a hopeful Nexus, but, hey, somebody's got to do it.