System Performance
The main downside to the Envy x2 is undoubtedly the performance. As we covered when testing the Snapdragon 835 running Windows, at best you'll get an entry-level experience, and at worst you'll be struggling through downright terrible performance in emulated x86 apps.
The Snapdragon 835 is a low-power processor with weak single core performance, so this level of performance isn't all that surprising. Looking at our benchmark results in native apps like Edge, you can expect performance above an Atom-based Celeron processor from Intel, but below most of Intel's Core processors from the past 3-4 years. You're just not going to get Core i5 performance Intel provides at 5 to 15 watts in a sub 3W power envelope.
The ability to emulate x86 apps on an ARM architecture is certainly impressive, especially at this TDP, but it's not something I'd recommend users actually do. The Celeron N3450, one of Intel's slowest x86 processors, is significantly faster in most x86 workloads, while the low-power Core i7-7Y75 obliterates it. And apps just feel sluggish to use, which isn't what you'd want from a premium tablet.
On top of this, you're faced with many limitations. The Snapdragon 835 can't run 64-bit x86 apps, it doesn't support x86 drivers, it doesn't support OpenGL newer than 1.1, and apps that customize Windows may not work. It's still very early days for x86 emulation on ARM, so for most use cases it's really a 'break glass in case of emergency' sort of thing.
Being limited to Windows Store UWP apps for decent enough native performance will be fine for a handful of users that like using Edge as a browser or watching videos and are fine with other basic apps and games.
But if you're used to using Chrome, or want to use productivity apps like Microsoft Office, Adobe Photoshop, or really anything built for Windows desktops, emulated x86 performance isn't going to cut it. Especially when there are so many productivity tablets out there using Intel processors that run x86 apps just fine.
The Envy x2's storage performance isn't particularly amazing either. The SATA SSD isn't going to break any speed boundaries, and while that's fine considering the rest of the device's performance, something a bit faster would have been nice in a high-end tablet.