I bought the DJI Osmo when it was released, these are my thoughts:
1. Silky Smooth Stabilization
Gymbal works very well, although not completely shake proof. One of the better ones out in the market.
2. Control Integration
DJI has done a pretty good job when it comes to integrating the controls to the the app and functionality of the unit. Since everything is proprietary to DJI, all of the controls works very well.
3. Low Distortion
Thanks to its 94° FOV 20mm f/2.8 (35mm format equivalent), the footage looks really well corrected since it has very little distortion. This is one of the main factor of me considering getting the OSMO vs. GoPro (which tends to have a good amount of distortion).
4. 4K package
4K is a big plus due to the ability to crop and the sheer size of its resolution. Most people probably don't need to shoot in 4K though.
Although the gymbal stabilization is very smooth, the camera can only be used with the gymbal, making it quite a big unit especially when you attach an iPhone to the side plus the external microphone (which you will need). There is no way to use the camera by itself.
2. Focus Issues
Also the camera on the OSMO is optimized to focus at 1m-infinity range despite it including a triple-tap selfie mode. This means that you (the intended subject of a selfie mode) will not be in focus while your background or what is behind you will be. This defeats the purpose of a selfie feature which is a big oversight by DJI. This clearly shows that they didn't design and test the product thoroughly before releasing it.
3. Audio / Lack of usable microphone:
What really killed it for me was the lack of usable built-in mic, which means I have to purchase a separate mic and make the whole package even bigger. The built-in internal microphone is practically useless as the gain levels are low and most of the audio capture is the sound of rotating motor from the gymbal or the fan noise. Very disappointing.
4. Gymbal Motor and Fan Noise
The unit runs hot, and you will definitely notice the buzzing noise from the fan unit inside the OSMO. Also the unit runs very hot after a little use (GoPro Hero 4 Black does this too)
It is definitely not aimed at the action cam market like a Gopro, however my overall take on the DJI Osmo is that its still is a prototype at best. It would be interesting to see what they come up with on the next version. I really hope that they will release a proper version where all the parts work properly and there is no oversight in functionality and design like its built-in mic and the lens focus.
Also if you are going to buy this, don't buy them direct from DJI. Their customer service is terrible to say the least. Trying to get my refund is a nightmare, I was quite close to filling a credit card chargeback because they took so long (1 month) to refund my payment. There is a lot of ball-kicking since their customer service hq is in China, so they had to contact the US office and see if they receive it back yet and what not.