The Samsung Galaxy J5 (2017) measures 146.2x71.3x8mm - a whole millimeter narrower than the outgoing model, which is the metric that we've established to matter the most. Hence, the 0.1mm shaved off the thickness and the 0.4mm increase in height can be dismissed as irrelevant. The J5 (2017) is more compact than the J7, and that is likely one reason you'd go with the 5 and not the 7 (that, and price, of course).
Perhaps more importantly, however, the J5 (2017) is tangibly lighter than the J7 - at 160g, the smaller model will put less strain on your pocket than the 181g J7. If lighter is what you're after though, a Moto G5, an Xperia XA1, or a Huawei P10 lite might be viable options at around 145g. The dual-glass Galaxy A5 (2017) is 3g lighter than the J5 - unlikely to make a difference.
Once plastic phones true to the traditions of Samsung of old, the J-series have evolved to the more premium metal unibody designs we see today. The downside is no more removable batteries, but the number of people still insisting on swapping batteries seems to be dwindling, so we should just move on.
Having done just that, we can appreciate the smooth matte finish of the aluminum back that flows nicely into the rounded sides. The finish handles fingerprints well, as in it doesn't pick up too many to begin with, they're not readily visible, and are reasonably easy to clean. The J5 (2017) is decently grippy, though the old plastic build did allow a firmer hold.
The antenna band styling is quite refreshing - instead of trying to mask the strips, Samsung's designers have made them stick out. Not a new approach, strictly speaking, but it does work on the J5 and J7 for 2017. The camera and flash are positioned alongside the central axis, and the assembly doesn't stick out from the back - if anything, it's marginally recessed.
It's classic Samsung on the front - a Super AMOLED display takes center stage with the good old hardware Home button under it, as is the case with Samsung's phones with finite displays (as opposed to the Infinity Galaxy S8). There's a fingerprint sensor embedded in the Home button, so it's not merely a button.
The capacitive Recent tasks key is to the left of Home, and the Back key is on the other side. They're not illuminated, but the contrasting markings are decently visible.
Above the display next to the earpiece is one major upgrade the 2017 model brings over last year's: a 13MP selfie cam, compared to the 5MP front-facer of 2016's J5. There's an ambient light sensor too. What's missing is a notification LED, which is fine on the J7 with its Always-on display, but since the J5 omits that feature an LED would have been appreciated. Well, there is an LED, but it's the front flash - it's something.
The power button is (where it should be) on the right side, and next to it you'll find the single loudspeaker. Introduced with this year's A-series, this alternative placement makes sense, particularly for landscape use. You're unlikely to block it, and it fires towards you.
On the left side there are the volume controls - two separate buttons instead of a rocker. Two separate card slots allow you to insert up to three cards - two nano SIMs and a microSD. That's for the dual-SIM version though; our single-SIM variant will obviously only take one SIM.
The J-series don't get a USB-C interface - it's the microUSB 2.0 port that you'll find on the bottom of the J5 (2017). To its right there's a 3.5mm jack, and on the other side a pinhole reveals the location of the microphone.
The way the J5 (2017) fits in your hand is no small part of the reason why people will chose it over the J7. It's more compact, and reasonably comfortable for single-handed use.