*** Update #2 ***
No change in rating but I do want to offer a few points of clarification. Anker reached out to me regarding my review and offered a clarification and a chance to review another of their products. First the clarification: the Anker PowerCore + mini is a 1A device, whereas the RAVPower 3350 is a 2.4A device. Therefore, it makes sense that the RAVPower will offer the benefits discussed below. However, my review was based upon similar sized and priced devices and comparing the two I would still recommend the RAVPower over this Anker device.

However, I don't recommend either now. Anker also provided me a free device, the Anker Astro E1 6700mAh (<a data-hook="product-link-linked" class="a-link-normal" href="/Upgraded-to-6700mAh-Anker-Astro-E1-Candy-Bar-Sized-Ultra-Compact-Portable-Charger-External-Battery-Power-Bank-with-High-Speed-Charging-PowerIQ-Technology-Black/dp/B06XS9RMWS/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">[Upgraded to 6700mAh] Anker Astro E1 Candy-Bar Sized Ultra Compact Portable Charger, External Battery Power Bank, with High-Speed Charging PowerIQ Technology (Black)</a>). It is similarly priced (slightly higher price, but in the same range) and similarly sized (slightly larger, but in the same range) and offers more charge (6700 vs. 3350). The trade-off on price and size charge are worth it. Also, the Anker E1 does not get hot, even during fast charge. I really liked the E1 device and recommend that device over both the RAVPower and Powercore+ mini.

*** Updated #1 ***
Dropping to 3 star (from 5 star) after using the RAVPower Luster Mini 3350mA (<a data-hook="product-link-linked" class="a-link-normal" href="/RAVPower-Luster-Mini-3350mAh-Portable-Charger-External-Battery-Pack-Battery-Bank-Most-Compact-Power-Bank-with-iSmart-2-0-Technology-2-4A-Output-2A-Input-for-Smartphones-and-More-Black/dp/B00ZZYBAI2/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">RAVPower Luster Mini 3350mAh Portable Charger External Battery Pack Battery Bank Most Compact Power Bank with iSmart 2.0 Technology (2.4A Output, 2A Input) for Smartphones and More (Black)</a>. The RAV has more capacity (effectively) and a much faster power charge (with very similar heat generated).  No downside to the RAV as compared to the Anker.

*** Original Review ***
I purchased the Anker power bank for a recent trip. My aging phone has been overheating and burning through battery life and needed to have back-up power for my trip through various amusement parks. The Anker worked great in providing daily charge to my phone. No overheating (wish I could say that for the phone) and still provided very fast recharging. It was a great, small profile. At times I forgot I had it in my pocket.
*** Update #2 ***
No change in rating but I do want to offer a few points of clarification. Anker reached out to me regarding my review and offered a clarification and a chance to review another of their products. First the clarification: the Anker PowerCore + mini is a 1A device, whereas the RAVPower 3350 is a 2. 4A device. Therefore, it makes sense that the RAVPower will offer the benefits discussed below. However, my review was based upon similar sized and priced devices and comparing the two I would still recommend the RAVPower over this Anker device. However, I don't recommend either now. Anker also provided me a free device, the Anker Astro E1 6700mAh (<a data-hook="product-link-linked" class="a-link-normal" href="/Upgraded-to-6700mAh-Anker-Astro-E1-Candy-Bar-Sized-Ultra-Compact-Portable-Charger-External-Battery-Power-Bank-with-High-Speed-Charging-PowerIQ-Technology-Black/dp/B06XS9RMWS/ref=cm_cr_arp_d_rvw_txt? ie=UTF8">[Upgraded to 6700mAh] Anker Astro E1 Candy-Bar Sized Ultra Compact Portable Charger, External Battery Power Bank, with High-Speed Charging PowerIQ Technology (Black)</a>). It is similarly priced (slightly higher price, but in the same range) and similarly sized (slightly larger, but in the same range) and offers more charge (6700 vs. 3350). The trade-off on price and size charge are worth it. Also, the Anker E1 does not get hot, even during fast charge. I really liked the E1 device and recommend that device over both the RAVPower and Powercore+ mini. *** Updated #1 ***
Dropping to 3 star (from 5 star) after using the RAVPower Luster Mini 3350mA (<a data-hook="product-link-linked" class="a-link-normal" href="/RAVPower-Luster-Mini-3350mAh-Portable-Charger-External-Battery-Pack-Battery-Bank-Most-Compact-Power-Bank-with-iSmart-2-0-Technology-2-4A-Output-2A-Input-for-Smartphones-and-More-Black/dp/B00ZZYBAI2/ref=cm_cr_arp_d_rvw_txt? ie=UTF8">RAVPower Luster Mini 3350mAh Portable Charger External Battery Pack Battery Bank Most Compact Power Bank with iSmart 2. 0 Technology (2. 4A Output, 2A Input) for Smartphones and More (Black)</a>. The RAV has more capacity (effectively) and a much faster power charge (with very similar heat generated). No downside to the RAV as compared to the Anker. *** Original Review ***
I purchased the Anker power bank for a recent trip. My aging phone has been overheating and burning through battery life and needed to have back-up power for my trip through various amusement parks. The Anker worked great in providing daily charge to my phone. No overheating (wish I could say that for the phone) and still provided very fast recharging. It was a great, small profile. At times I forgot I had it in my pocket.