The Samsung (NASDAQOTH: SSNLF) Galaxy S6 is sure to be one of the best smartphones released this year. With its ultra-fast processor, high-resolution display, and more premium body, Samsung's flagship is more technologically advanced than Apple's (NASDAQ:AAPL) iPhone 6.

But in its quest to challenge Apple, Samsung might lose many of its best customers.

Although the Galaxy S6 is undoubtedly better looking than its predecessor, its design entailed many compromises -- most notably, the loss of the Galaxy's trademark removable battery and expandable storage.

A smaller battery that isn't replaceable
The battery in the Galaxy S6 could last longer than its predecessor -- Samsung has reworked its software, trimming out many unnecessary features, and equipped the phone with a more power-efficient processor -- but owners won't have the ability to replace it on the fly. Like Apple's iPhone, Samsung's flagship Galaxy now sports a unibody design. That means no removable back plate, and thus, no removable battery.

Samsung was able to limit this transgression somewhat, by implementing rapid recharging. In as little as 10 minutes, the Galaxy S6 can draw enough power from its charger for four hours of use; in total, the Galaxy S6 recharges twice as fast as Apple's iPhone 6. Yet nothing can truly replace the ability to go from 0% to 100% in a split second, a feature only possible with a swappable battery.

Samsung embraces Apple's storage tiers
Since the very first model, Apple has sold its smartphones with various tiers of storage. They've changed over the years (4 GB and 8 GB became 16 GB and 64 GB), but have always been offered in a good-better-best format. Samsung, in contrast, has shipped its phones with a set amount of storage, but offered customers the ability to expand that storage with an SD card.

No longer. The Galaxy S6, like the iPhone, is limited to its internal memory. As with charging, Samsung has one-upped Apple in this department: Its entry-level model will ship with 32 GB rather than 16.

But it's still a step down from Samsung's old phones. The Galaxy S5 has just 16 GB of internal memory, but can support SD cards up to 128 GB in size, for total storage of 144 GB. The Galaxy S6, though, maxes out at 128 GB of storage, and paying for that extra storage space will likely cost far more than a similarly sized SD card.

A move in the right direction, or a massive mistake?
Samsung made other compromises with the Galaxy S6's design; for example, unlike the Galaxy S5, it's not waterproof. But that feature was never a Galaxy mainstay -- the loss of the SD slot and removable battery seems far more substantial.

Samsung hopes its premium design will win over more buyers than its loses -- and it might. Other Android OEMs, such as HTC and Motorola, abandoned the removable battery years ago. The SD card slot is still somewhat common (HTC's new One M9 retains it) but not universal -- Google's Nexus phones and the Moto X don't have one. LG is perhaps the one handset manufacturer that could benefit the most from Samsung's decisions, as its current G3 flagship has both a removable battery and an SD card slot.

Given its use of the Android operating system, Samsung's customers could more easily defect to rival handset vendors than could Apple's. Whether they will remains to be seen, but Samsung has certainly taken a gamble with its latest flagship.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.