For as long as GoPro cameras have existed, they've been rectangles. While the little video cameras certainly do their jobs very well, a rectangular camera can be awkward to mount on your head or your board, and the shape certainly isn't very hydro-dynamic. GoPro hopes to fix the problem of awkward bulk by introducing an entirely new form-factor: a cube!

The new Hero4 Session, which goes on sale July 12 for $400, is a real-deal action camera from the leader in action cameras. It's waterproof without a case, and it's tiny enough that it almost disappears once you've mounted it. With all of these improvements, the Hero4 Session is a big step forward for GoPro in some ways, but it's a step backwards in others.

Let's start with the basics. The Session is a 1.5-inch cube that weighs only 2.6 ounces. It's waterproof to 33 feet on its own, and doesn't require any additional housing. In its included frame mount, the Session is 50 percent smaller than a Hero4 Silver or Black is inside its waterproof shell, and it's 35 percent lighter, too. We've seen this form-factor before, most notably from last fall's Polaroid Cube. The Cube was just splash-proof, though, and had lousy resolution and frame rates, where as the Session is an honest-to-goodness action camera. Speaking of resolution and such, here's what the Session's got:

• 1080p at 60 and 30fps (SuperView at 48 or 30fps)

• 1440p at 30fps

• 960p at 60 or 30fps

• 720 at 100, 60, or 30fps (SuperView 60 or 30fps)

• WVGA at 120fps

• Stills at 8MP with 10fps bursts

Notice anything conspicuously absent? Where's my cinematic 24 fps? That's my go-to mode for shooting less actiony stuff. Also, 720p at 100fps? 100? Are we suddenly on the PAL system here? Weird. You have the option of enabling the Protune feature (which gives you a higher bitrate), but then you're limited to 1440p at 30fps, 1080p at 60 or 30fps, and 960p at 30fps, and you don't have all the tweakable options you do with your standard Hero4 cameras in Protune. Some strange choices here.

More annoying is that you can't change modes on the camera itself. You can start/stop video using whatever settings you last had it set for, and you can start/stop time-lapse mode by long-pressing, and that's it. If you want to change any setting you need to pair the Session with the GoPro app on your phone or with a Wi-Fi remote control (sold separately for $80). It's weird because the Session has two buttons and a display, which was all GoPros had for years, and in other models, you were able to change setting directly on them. Maybe the company can fix this with a firmware update.

Ready for Action

The good news is that the smaller design is a success. I went swimming with it strapped on my back, and then on my chest. Normally there's so much drag on your standard GoPro that it bounces around on you, slowing you down and ruining your shot, but not with the Session. I could barely feel it, and the imagery turned out nice and smooth. No problems with leakage, either, even when jumping off a 15 foot ledge or when I was being pounded by some surf.

The Session comes with two frame mounts. One is your standard upright affair, and the other allows the camera to be mounted more or less flush against a surface. Because the cam is a perfect cube, you can orient it inside the frame in whatever direction you please. This means you finally can attach a GoPro to the side of something without having to use an awkward and shaky triple-jointed hinge mount.

I found battery life to be excellent, and this is because when the Session isn't recording it's powered off. I didn't think it would make much of a difference, but in practical usage it nearly doubled the endurance of my Hero4 Silver. Really impressive. And that's good because the battery is built-in and not swappable. The trade-off here is that because it has to power-up every time you start recording there's a delay of four seconds after you hit the button before you're rolling, which is definitely long enough to miss something important.

Audio is quite decent for a waterproof camera. The Silver sounds a lot better when it's outside its waterproof case, but once it's under all that plastic the Session definitely outshines it. The Session's mics are also specially designed to be able to drain quickly when wet, so there isn't a long delay in restoring audio quality after a splash. I found that this generally works very well, though the drainage mechanism struggles if the camera is mounted upside down. Audio is designed to dynamically shift between the two mics, so if the one in front is getting blown out from wind, it'll shift to the hopefully quieter one in the back. It's a good idea, but I didn't notice any major difference.

Jagged Little Pill

Now for the bad news. Image quality isn't very good. I mean, it's fine if you're just looking at it alone, and GoPro certainly managed to make an impressive ad out of footage from it, but try comparing it with the Hero4 Silver. The Session gets its doors blown off. Images on the Silver are far sharper, while the details on the Session look smudged. The Silver delivers excellent dynamic range and color depth, while the Session loses details in the shadows and its colors are bland and muted. The images you get off the Silver are far superior—no contest.

The Silver also gives you more options for frame-rates and resolutions, switching settings is easy, it's waterproof to 131 feet (with its included case), you can swap batteries when you run out, and it's got a built-in touchscreen for framing shots, reviewing footage, or tweaking options. It's just a much better camera—especially when you consider that costs the same as the Session.

Yep. The Hero4 Session will retail for $400, just like the Silver. I get that R&D is pricey, but selling a dumbed-down camera at the same price as the full-featured model doesn't make any sense for consumers. GoPro is trying to position the Session as the friendlier, easier-to-use, entry-level camera, so why charge the same money as the second-best camera (just behind the $500 Hero4 Black)? If it was $300, you could make a case for it. But there's just no good reason to buy the Session over the Hero4 Silver, which is still the camera I recommend for most people.

I like what GoPro is going for here. Reexamining form-factors is healthy, and if it could get the quality of the Silver into the body of the Session, it would be a killer camera. That's not the case, though. The Session's image quality is two generations behind the times, and the field is just way too competitive for that, especially if you're priced among the top-tier action cameras.

Choose Your Accessory

In other news, GoPro is also launching a handful of new mounts, some of which are very cool. First there's the Ball Joint Buckle, which is basically your standard GoPro clip with the ability to rotate the camera around 360 degrees without having to unclip it. One will come with every Hero4 Session and they'll be available separately, too, for a price that's yet to be determined.

There's also The Floaty, which you jam your Session into to keep it from sinking. It's made from the same kind of foam rubber they use for Crocs. That'll be 20 bucks.

My favorite new mount is The Strap (a.k.a. the Ironman, unofficially). It's very versatile and allows you to attach your camera to your hand, leg, arm, wrist, foot, etc. That'll run you $60.

There's also The Jam for mounting GoPros to musical instruments ($70, which is steep), and the Casey, which is GoPro's first storage/organization solution for your camera and all its little parts. Lastly, there's the WindSlayer, which is a windscreen made of foam that goes around your Hero3, 3+, or 4 when it's in the Frame mount. It muffles that rushing sound of wind which should result in less shrieky video. Twenty bucks for that.

The Hero4 Session and all of the mounts above will be available on July 12.