From smartphones and tablets to a $7,000 desktop, we’ve cracked open a lot of tech this year. And as we do at the end of each year, it’s time to take a look at a few of our favorites. During this special episode of Cracking Open, I’m counting down my top five teardowns of 2012.

5. Nokia Lumia 900

First on our list is the Nokia Lumia 900. Released in the Spring, this Windows Phone device was Nokia’s attempt to recapture some of the American smartphone market.

Unfortunately as we discovered during our teardown, the phone’s hardware just wasn’t up to par with the competition. I went so far as to call it mediocre. So why did I include our 900 teardown on this list, because it’s probably this year’s best example of why knowing what’s inside a device is an important factor in whether you buy one or not.

Just two months after releasing the Lumia 900, we learned that it wouldn’t be upgradable to Windows Phone 8. And despite huge marketing pushes from Nokia, Microsoft, and AT&T (including a 50 percent price cut three months after launch), the phone just never took off. Like the phone’s hardware, sales were just mediocre.

4. HP Z1 Workstation

In the fourth spot is one of the most expensive items in I’ve ever cracked open–a $7000+ HP Z1 Workstation.

The Z1 was unlike any other all-in-one on the market. It was packed with high-end hardware and designed to be both upgrade and repair-friendly. Its unique stand let the machine lie flat (for easy hardware access) and the case opened more like the hood of car than a computer. You could remove most of the internal components without using tools. And despite having six fans, it was remarkably quiet.

This machine was definitely one of the most unique, and enjoyable cracking opens of 2012.

3. Google Nexus 7

Third on our list is the highly anticipated Google Nexus 7. Assembled by Asus, the first Google-designed tablet had solid hardware, a good design, and a great price ($199). As I discovered, it was also a snap to crack open and had easily-replaceable hardware.

Even with the release of the Kindle Fire HD, iPad Mini, and Nook HD, CNET’s Eric Franklin still believes that overall, the Nexus 7 is the best small tablet you can buy. I agree.

2. Microsoft Surface with Windows RT

The second spot on our list is held by another highly-anticipated tablet–Microsoft’s Surface with Windows RT. Microsoft’s first Windows 8 tablet came with a quad-core, Nvidia Tegra 3 processor, 2 gigs of RAM, and several nice features like a microSD card slot, full-size USB port, and kickstand.

Unfortunately, it was also a pain to crack open and disassemble. As wrote in my original review, “hopefully, the Surface with Windows Pro, which is aimed at businesses, will be more repair-friendly.”

1. Apple 15″ MacBook Pro with Retina Display

We’ve reached the end of my top teardowns list, and sitting in the top spot is Apple’s 15-inch MacBook Pro with Retina Display. Unfortunately, like the Lumia 900, this machine is on my list for all the wrong reasons.

Like all MacBook Pro’s, the Retina version is well-built, has solid hardware, and its display really is gorgeous. But as I discovered during my teardown, it’s also nearly impossible to upgrade–thanks to RAM that’s soldered to the motherboard. And, it’s a pain to work on–thanks to tamper-resistant pentalobe screws and a battery that’s glued to the upper half of the case.

This was another example of why knowing how a device is put together and what’s inside it is critical when buying one. The last thing you want is to find out a year after you bought your Retina MacBook Pro that you can’t upgrade the memory.