Tl;dr
Video above has all the info, 8 hour to infinite battery life if near a USB plug. Average audio quality.
Mods, let me know if this is not allowed to post here, and I'll take it down.

Brief Summary
I just received and reviewed the Syllable D9x, a pair of true wireless Bluetooth headsets, Apple Airpod style with one really neat trick, replaceable batteries. Unlike the Airpods, the “stick” part of the Syllable D9x is a magnetic battery pack that easily snaps out and can be replaced in a few seconds.


Syllable D9x true wireless Earbuds Specifications:
Bluetooth 4.1, HFP, HSP, A2DP, AVRCP
8mm Driver
2x Earbuds, 4x batteries
80mAh battery
400mAh Battery Pack
Bluetooth Range: 20 Feet (6m)
Product size (L x W x H): 5.50 x 1.50 x 2.50 cm
Package size (L x W x H): 13.50x9.00 x 5.50 cm


Build Quality
Comes in a nice soft touch matte case, inside containing the earbuds, a cigarette lighter battery charger with 4 batteries, USB cable, eartips, and a carabiner clip to attach to your bag (although I don’t recommend it, its too easy to steal).

The earbuds are fairly average quality, about the same as the D900 Minis, plastic, however the magnetic battery port does have some stray plastic sticking out, causing any battery packs to sit slightly askew.

The magnets on the battery pack are very strong, the entire earbud is more likely to fall out than the battery pack by itself. If you push the magnet sideways, it won’t be enough to cause the battery to fall out, but it will be enough to sever the connection between the earbud and the battery pack, making the earbud turn off. Once the connection is restored, the earbud will turn back on and reconnect in 3-4 seconds, annoying, but not deal breaking.

The battery packs are metal as is the accompanying charging case, which can charge two battery packs at a time, and can charge 6 battery packs in total. Unlike the D900 Minis, the case has feedback when charging but not how much charge is left, slightly annoying.


Comfort/Fit
The stock tips fit in my ears perfectly. However, the battery pack does pull the entire earbud slightly down. That being said, these stay in very well, but it doesn’t feel that way. I shook my head quite vigorously and they didn’t fall out, but they fell out when I did a cartwheel. I took these out for a run with my puppy, and they didn’t fall out.
The metal battery part usually doesn’t touch your face but when it does and its below freezing, ooh its cold.


Aesthetics
Looks about the same as Airpods, depends how you feel about the prominent Syllable logo on each earbud itself.


Isolation
Hmm, not sure whether my idea of isolation matches what Head-Fi’ers in general think of. In my opinion its average, worse than the D900 Minis because the heavy battery pack pulls it out of your ear slightly if you move, but stays put if you don’t. Definitely better than Airpods, definitely worse than the Monoprice 8320 IEMs. Probably exactly in the middle.


Noise Cancelling
I added this section just to clarify, I had actually received some info from a source and from several webpages touting noise cancelling capabilities, there are none here, and those reviews that say otherwise are mistaking isolation for noise cancellation.


Bluetooth Quality
Range is below average, 6 meters no obstacles, 3 meters with walls and doors. I did experience some dropped connections between left and right earbuds, but not very often.


Battery Life
Each battery pack can power the D9x for 2 hours. The included case charges each pack in about 30-40 minutes. The charging case can charge 6 battery packs in total before running out of juice, meaning around 8 hours of battery life. You can charge the case while the case is charging the battery packs in turn. So if you are beside a wall charger, you can expect infinite battery life. However, one caveat, when you take the battery pack out of the earbud, it turns off. That means that whenever you swap a battery, can you expect music downtime of about 10-15 seconds, depending on how fast you are.


Audio Quality
Audio is average, passable. They are a lot more balanced than the D900 Minis (read less bass, but I love bass), I think it has a slight edge on clarity vs the D900 Minis, fairly clear even with complicated tracks. Less boom than the D900 Minis which would have come in handy for movies and TV shows, but nonetheless, fine.
Quality here is perfectly useable for listening to music while working out at the gym or watching a TV show.


Value for Money
MSRP is $80USD, fair price to pay for “infinite battery” and average audio quality, but its on sale for $60, and at that price its pretty good. I think the best use case is a student who wants true wireless earbuds while studying, they can plug the case into a laptop and have infinite music while cramming. You could also watch infinite movies also if you wanted to.