This has replaced my "vaguely smart" Fitbit Surge.
What I was most looking forward to with this watch was the ability to receive email notifications to my wrist for work. I already had txt and call notifications, so the addition of email was always going to be a bonus.
My first impressions are thus:
Battery Life:
Day one, I got around 24hrs of battery...mainly due to the fact that I didn't leave the watch alone for more than a few seconds at a time. This included changing watch faces every few minutes, loading and removing apps at random and setting the backlight to come on at it's brightest setting for the longest duration as often as possible (don't ask).
Days two to seven...it's only been charged again once since the first day...5 days' battery life seems accurate - even with around 150 notifications a day.
Screen:
It's no Amoled beauty, but I find that the screen works well for all that I require of it.
Yes - it's low-res, washed-out when backlit and a bit small, but it's a smart watch...not a small iPhone/Galaxy on my wrist
In bright sunlight or under bright lighting, it's fantastic - so easy to read and sharp as a tack.
Under the backlight, it is washed out and insipid, but still easy to read and does its job well.
Watch Faces/Apps:
When they say there are over 8000 apps for the Pebble, they are not kidding.
Many of them are just awful - home-brewed for specific purposes or just for fun, probably by 8 year-olds.
Some of them are just brilliant. Two in particular stand out. Headlines (allows the reading of BBC headlines on the wrist) and Pandora (which allows you to control Pandora on your phone from your wrist).
Watch faces are plentiful. I've loaded around 70 into the app and of those, I have 50 on my watch, ready to use within seconds.
Current favourites are: TimeStyle, YWeather, Analog (looks a lot like the analogue Apple Watch face), DIN Time and Real Weather.
Most of these have the time, date, day, current weather, temp and battery life left on them. Some show a graphic of the current weather conditions (which can also be seen by looking at the sky) and others show a forecast in addition to the current conditions/temp (see DIN Time).
The vast majority are very customisable, regards colours, info etc as well.

DIN Time (above)

Real Weather (above)

Analog for Pebble Time (above)

Headlines for Pebble Time (above)
Software/UI:
The Pebble Time uses a UI called Timeline.
This allows for a quick glance from your current watch face into the future or the past (from sunrise to sunset, including all of your appointments and anything else you choose to have added to your timeline)
I find this to be an efficient and easy to understand use of the watch's smarts.
The various reviews I read are actually really accurate and do the Timeline UI justice.
I find it great.
The one thing I did find it hard to get used to was the sheer frequency of alerts...basically anything that I have going to the Notifications list on my iPhone sent me an alert to my watch. This I adjusted in the settings of my iPhone and I managed to reduce the number of alerts I was getting...but I am still getting around 150-200 a day including work email, texts and calls, along with calendar alerts.
Using buttons instead of a touch screen was a bit odd to start with, but after the first epic day of usage, I was used to it and haven't really looked back since...in fact I see it as an advantage - no accidental taps/swipes to contend with.
Comfort/Style:
The Pebble Time is surprisingly light and comfortable on the wrist.
It's standard silicone/polymer strap is comfortable and flexible, but I did =swap it our for a nice leather one I had at home (straps are swappable for any 22MM watch strap that you have or can buy).
I've since gone back to the standard strap - it's comfortable and durable.
The Bezel is polarising - some people hate it with a passion. Personally, I like it - the metal looks good and it adds a sense of solidity to the otherwise plastic watch.
The border around the actual screen (as seen in the pictures above) is a bit off-putting, but if you use a watch face that has a black border/background, you don't even see it...so it's a moot point for me.
Conclusion/Overall Impressions:
Overall, I am very impressed with my Pebble Time.
It does what I want it to do and it does it well.
The screen could be larger and brighter and touchier...but then I'd lose the reason for having this particular device...the battery life.
Nearly a week of battery life, with a fair amount of use and notification action, is pretty spectacular.
If I was on holiday and simply had calls/txts going to the watch, I would think I'd get at least 7 days out of it.
Would I recommend one?
Yes...but you have to realise this is NOT an Apple Watch or an Android Wear LG Urbane...
Has it made me pine for more? Yes. I'd love an Apple Watch that has a week-long battery and always-on watch face. But that doesn't exist...whereas the Pebble Time does.
This will be my go-to watch for quite some time (forgive the pun) to come.