Laplets like the  Microsoft Surface Book are taking over in business.  One recent survey suggested that the Apple iPad is on the decline as the Surface jumped in market share by 9%. There's a reason smart business users and savvy travelers choose these 2-in-1 one machines. They work as a fully functional laptop and, when you disconnect the screen, work fine as a tablet for movies, swiping through photos, and playing games on the plane.

I like the term laplet for any device that functions as a real laptop and a tablet. There's some debate over when to use the term, but the Lenovo ThinkPad X1 matches up nicely with my definition. It's more like the  Surface Book than the Surface Pro 4, only because the keyboard feels like it can withstand some abuse and is made from a thicker plastic that protects the tablet when it is folded up in your satchel or stuck in a tablet sleeve. Yet, it's also more like the  iPad Pro because it works as a "real" tablet without quite as much weight and bulk.

The specs bear this out. The X1 tablet with keyboard is .3-inches thin and 2.4-pounds. The Surface Book weighs 3.34 pounds in laptop mode with the keyboard, so it's almost a pound heavier. The iPad Pro, at .27 inches thin, is about the same thickness as the Lenovo X1, although the X1 is heavier by a full pound. If you have to choose between the iPad Pro and the X1 for the size, they are remarkably similar and both have a 12-inch screen.

In my tests, the X1 proved to be a capable laptop. The keyboard keys offer a hint of what you get with a regular ThinkPad laptop. They are springy, easy to find, and rigid enough for fast typing. You won't slip off the screen as you will with some "chiclet" thin key keyboards. And, the keyboard is definitely beefier than any cover keyboard I've tried, especially the one that works with the iPad Pro. That said, the X1 keyboard did tend to sag a bit even as my fingers kept flying.

The included pen worked remarkably well in the Microsoft OneNote note-taking app, allowing me to jot down notes in a meeting and draw out ideas. Lenovo offers an app called WRITEit that converts what you write with the pen to text, but it didn't quite work right. In fact, the one included within Windows (part of the soft keyboard) worked better. Not a big deal, but I'm looking forward to someday writing an entire article on long hand just to prove it is possible. Not quite there.

Things get much more interesting when you realize how much you can customize the X1. These modules are not available quite yet, but there's one called the Productivity Module that costs $150 and adds about five hours of battery life to the already acceptable ten hours on the X1. (The extra battery will come out by the end of May.) A 3D Scanning Module will cost $220 and allows you to scan objects in front of the X1 in 3D so you can manipulate them and output them to a 3D printer. A Projector Module will cost $280 and projects a 60-inch image in front of the tablet. All of these modules snap in as easily as the keyboard using magnetic connectors.

This turns the X1 into a highly flexible business machine. Going to a meeting? Bring the projector module to show a presentation on a whiteboard. Need a battery boost? Bring the battery module. I could see Lenovo making modules with a better camera or speakers, and even expanding into area likes document scanning and printing.

You do get an overall impression about the quality and usefulness of any gadget during the test period, and the X1 is in the upper register where I'd bring it on a plane and use it at a hotel. It might not become a primary work machine only because I prefer a stiffer keyboard. The system is pretty high-end. It supports a fast Intel Core i7 processor, up to 16GB of RAM, and a 512GB flash drive. There's a standard USB port and one USB-C port. Audio sounded loud and clean playing Radiohead.

I liked it nearly as much as the Apple iPad Pro, the  Apple MacBook 12-inch, and the Google Chromebook 2015. When the extra modules come out, it will give me pause and make me think hard about replacing one of those favorite devices. It's an excellent tablet and a good laptop. If you find anything as versatile and expandable, be sure to let me know.