With two Galaxy S minis under its belt, Samsung has set off on a quest for a third, hopefully more successful version of its current flagship. But the rules have changed and Samsung has finally stopped ignoring this fact. While Sony flipped the mini game into a compact battle with higher stakes Samsung continued pushing minis that only look like their bigger counterparts but don’t offer nearly as much in terms of specs.
The Galaxy S4 mini was the last attempt and it wasn’t up to the task. It offered lower than Retina-grade pixel density, an inferior chipset and overwhelming price to finalize a product that didn’t stand too well next to the Galaxy S4.

The Galaxy S5 upped the ante even further and now Samsung had to finally equip the mini accordingly so it’s up to the challenge. This year’s mini, the Galaxy S5 mini, has a bigger Super AMOLED and has finally passed the HD and 300ppi barrier. The camera is still 8 MP, which is half of what the Galaxy S5 offers but the water resistant body, the IR blaster, the gimmicky hear-rate monitor and the fingerprint scanner are all there. The design is the same as well and the S5 mini comes in all four color options.
Key features:

Optional Dual SIM version available
LTE connectivity
4.5″ 1280 x 720 Super AMOLED display with 326 ppi
Android OS v4.4 KitKat with TouchWiz UI
Quad-core 1.4 GHz Cortex-A7 processor, Exynos 3 Quad 3470 chipset, Mali-400MP4 GPU, 1.5GB of RAM
16GB built-in storage, microSD card slot
8MP camera with LED flash, 2.1MP front-facing camera, 1080p video recording
IP67 certification for dust and water resistance
Fingerprint scanner with PayPal payments support and private mode access
Heart-rate monitor
Motion and gesture features, Air view
2,100mAh battery

Main disadvantages

Uncompetitive price at launch
No TV-Out option (MHL is not supported)
Only the LTE variant has NFC
Lacks in-call noise-cancellation

Source GSM Arena
http://www.gsmarena.com/samsung_galaxy_s5_mini-review-1116.php