This is not my first Android Wear smartwatch. For reference, I have been using an LG G Watch R for 2 years now.
The battery life is completely unacceptable on the Gen 3 Explorist. I am used to using the 'always-on' display, also known as Ambient mode. Didn't have any problems with my previous LG model. With Ambient mode enabled, I would remove my watch from the charger at about 7:55 every morning. It would be dead by 6pm. That's about 10 hours of battery. The battery life was so terrible, compared to my 2 year old LG, that I assumed something was defective with the watch. I took it back to the Fossil store and they happily exchanged it...no problem there (points for customer service!). The store manager also recommended I try disabling Ambient mode. The battery life on the 2nd watch was identical to the first. I tried disabling Ambient mode, and that does extend the life a little. I am now routinely able to get from 7:55am to 8pm, nearly 12 hours, provided that I do not actually use the watch much.
Other issues: the display is funky - it has relatively poor viewing angles. I am not able to read the watch on my hand, when my hands are on the steering wheel (left hand, 10 o'clock position). That wasn't an issue on my older LG model either. Also, I am a relatively heavy user of Google Assistant. For unknown reasons, the watch *always* fails to interpret the voice command when pressing the crown to activate the Assistant. Haven't been able to make that work even once. Interestingly enough - it works fine when you enable the Google Assistant 'Always Listening' mode. In that mode, you activate it just by saying 'OK Google.' But of course, then the watch microphone is always listening, and the battery life drops by about 40%.
Both the original watch and the replacement watch have experienced screen glitches, where the screen is covered with green flickers. The only way to recover is to reboot the watch (which also takes a big chunk of battery).
Also of note - the charger puck has fairly weak magnets. I found it difficult to keep the puck attached to the phone...the slightest jostle of the cable would cause the puck to fall off. The puck also has a definite 'front' and 'back' - only 1 side will charge the phone. However, the only indication which side is correct is a light gray icon on the white puck - very difficult to see in low light. The induction charging is fairly slow. A quick 1/2 hour charge (say at 6pm when the watch dies, while you're freshening up from work to go to dinner) will not get you through an evening out.
I found the Fossil watchfaces to be uninspired and rather low-resolution...there are much better ones available on the Play store. Do not buy this 'name brand' watch expecting high-quality watchfaces.
Build quality of the watch itself (excluding the charging puck) is very good. Metal clasp works good, haven't had any problems with it falling open. Sizing the band would be a pain if you don't have the right tool. I feel that Fossil should have offered to size it in the store.
Packaging and presentation was unimpressive.