Windows 10’s official birthday is July 29, but we couldn’t wait that long to unwrap the present. Build 10240, released Wednesday, is just a few buffs and polishes away from the final version, according to Microsoft. While we work on our full review, we can already provide you with the highlights.

It's worth noting that this preview, and our upcoming review, cover a pivotal moment in time for a Windows 10 that will technically never be done. Microsoft’s new Windows-as-a-service model means the software will continually improve and evolve.

This moment shows an operating system that blends some of the best of Windows 7 and Windows 8, while new features like Cortana and Windows Hello point to a very intriguing future. But I have very mixed feelings about one key component—let’s call it a rough Edge.

1. The Start menu and the Windows 10 experience

Because the Start menu is an important part of the initial Windows 10 experience, Microsoft needed to get this right. In large part, it has.

Microsoft treats the new Start menu as a dashboard, rather than a launching pad, and that’s a perspective I can get behind. I personally think that the Start menu works best when the Live Tiles are set up to deliver snippets of useful information: your calendar, photos, the top headlines, and more.

MARK HACHMAN The Start menu's back, and better on some ways, melding the list view with Live Tiles.

I’m a little less certain how users will respond to the layout, though. I haven’t seen anything that jumps in front of users and introduces them to the Windows 10 experience, or even tells you what “Microsoft Edge” is. You scoff, but Microsoft says only six percent of users use ALT-TAB to bounce from one app to another. There are numerous unskilled Windows users out there, and they're going to need some handholding.

However much we resisted Windows 8, it taught Windows 10 a thing or two. Using the ”Task View” or virtual desktops on a laptop feels very natural at this point, and I have to remember that snapping four apps to a large monitor (by dragging the windows into the four corners) hasn’t always been part of Windows.

2. Cortana, the Windows 10 assistant

I love the notion of digital assistants. I feel like we’re on the cusp of another culture-changing technology, and Cortana, Google Now, and Siri could evolve into something truly useful. Cortana has an enormous advantage here, as Windows 10 will be in front of your eyes for eight hours or so at the office.

Mark Hachman Cortana’s default view provides you with an overview of your workday. It’s somewhat redundant with the Live Tiles.

Right now, I really like the ability to tap Cortana’s search bar and see a summary of useful information—a slightly different take on the Start menu’s Live Tiles. I still see room for improvement, though. Rather than create a “notebook” of likes and dislikes, for instance, I’d like Cortana to learn through some quick thumbs-up/thumbs-down responses what interests me. And while I like asking questions of Cortana, there isn’t a good way of telling what she’ll respond to, and that’s a problem.

3. Microsoft Edge, the browser gone astray

The Edge browser is Windows 10’s problem child, something that could drag down the review. My beef with Edge can be summed up neatly: It’s dull, some of its vaunted features are overplayed, and it struggles to compete with its chief competitor, Chrome.

Mark Hachman At its worst, Microsoft’s Edge browser is like a foggy day in London.

Open Edge, and you’re met with a sea of gray. For all the complaints about Windows 8, Bing, MSN and its related content properties welcomed you. If I were Microsoft, I’d set Bing.com as the homepage and damn the critics.

I’m going to leave some of the more detailed critiques for the review. But I’ll say this: I created a stress test of 30 tabs, from Amazon to CNET to iMore to Salon. Edge tabs hung, stuttered, and became unresponsive, pegging a Core i5-based HP Spectre at 98% CPU utilization and 97% of the available memory. Using the same tabs, Chrome hit 59% to 70% CPU, and 78% memory utilization. Edge may indeed be “blazing fast” on the benchmarks, but right now, Chrome wins in my everyday usage.

4. Windows 10 apps: a mixed bag

Remember, so-called Metro/Modern/Windows apps are now windowed, and can roam onto the desktop. I’ll dive deeper into some of these in the full review, but for now, let’s play the lightning round: Photos, powerful; the Store, meager; Solitaire, high-energy; Music, blah; and Maps? On the cusp of becoming a very good app.

Mark Hachman Under the hood, Microsoft’s Windows 10 Photos app is surprisingly powerful.

I’m disappointed Microsoft decided to kill some MSN apps, including Health & Fitness. But as much as I’d have liked Microsoft to hold onto its extra content, they really don’t have a place in Windows 10.

5. General stability

Here, I think Microsoft has made significant strides. I was shocked when a recent build gave me a Blue Screen of Death—I can’t remember the last time I’d seen that in a Microsoft OS, period. But as I pointed out a few weeks ago, I've had some tough times with Windows 10.

MARK HACHMAN I like how Microsoft is trying to de-emphasize passwords and other complexity within Windows 10. This is asking for a 4-digit PIN, not a password.

I can’t say for certain if any game-changing bugs lurk out of my sight (if you have any suggestions for things to test, please let me know in the comments below). The most annoying thing I’ve seen is Windows 10’s tendency to forget about an external display if the PC was left idle for a length of time. But in the two most recent builds (I’m typing this on Build 10240 right now) that issue seems to have disappeared. I’m still seeing some inconsistencies connecting over ethernet and Wi-Fi, however, and that shouldn’t be happening. Also, my Surface Pro 2 refuses to rotate the display into portrait mode when undocked, a bug Microsoft blames on a driver issue.

6. Windows Hello

Walk up, look in, log in. Done.

MICROSOFT

Basically no one has a PC equipped with the depth cameras needed to enable Windows Hello. I had to borrow a Microsoft demo machine. But boy, Hello is terrific. You simply “train” the machine by letting the PC camera look at you for a moment or two. Thereafter, when you sit down at your PC, it recognizes you and logs you in—no effort required. And if you share that PC with others in your family, it will recognize them, too, automatically logging them in and picking up where they left off. This could be a huge win for Microsoft. When we all have the hardware.

So what’s the verdict?

No, we’re not giving that away just yet. But here’s what I can tell you: As a vision, the scope of Microsoft’s ambition for Windows 10 is breathtaking. What we plan to review for July 29 is simply one facet of it. Windows 10 is an ecosystem, spanning the PC, tablet, phone, HoloLens, and Xbox One.

I have some concerns that it’s trying to do too much. I also worry that aesthetics and latent bugs will hobble Windows 10. But as I craft my review, there’s no denying that Windows 10 feels like a tribute to the best of Windows 7 and Windows 8, and it moves the ecosystem forward.

We’ll tell you what we really think of Windows 10 a little later. But for right now, let’s start the conversation: What’s your (nearly final) verdict, and—more importantly—what do you think will be most important to evaluate once the RTM build is finally released?