Samsung is widely considered to have swung and missed in 2014 with the Galaxy S5 smartphone.
Despite featuring a wealth of what were top-end components, many buyers felt that the Galaxy S5 was slightly dull and contained too much gimmicky bloatware.
As a result, sales of the Galaxy S5 failed to meet Samsung's sales projections and led some to question whether the firm's time as the world's top selling phone vendor was coming to a close.
However, Samsung made a sweep of radical changes in its phone division and launched the completely redesigned Galaxy S6 at MWC in Barcelona in March.
To see how the Galaxy S6 compares to the One M9 and iPhone 6 you can also check out our triple head to head review.
Design and build
The Galaxy S5's design was a key sticking point for buyers, many feeling that it was all but identical to its predecessors and had a flimsy, cheap feel.
There is a lot of truth to this claim and the Galaxy S5 has the same slightly curved 'pebble' design with metallic sides, detachable polycarbonate back and Gorilla Glass front as the older Galaxy S4 and Galaxy S3.
The only noticeable difference between the Galaxy S5 and its predecessors is the backplate's slightly perforated texture.
Aware of buyers' complaints, Samsung completely rethought its design strategy in creating the Galaxy S6. Borrowing design elements from Apple and Sony, the Galaxy S6 has metal sides and Gorilla Glass back and front.
The design is a big improvement on the Galaxy S5 and makes the Galaxy S6 feel noticeably more premium and top-end.
Additionally, Samsung has managed to make the Galaxy S6 thinner and lighter than the 142x73x8.1mm, 145g Galaxy S5 at 143x71x6.8mm and 138g. The lighter weight and thinner frame make the Galaxy S6 more comfortable to hold.
Interestingly, unlike the Galaxy S5, the Galaxy S6 is not IP67 certified, meaning that it won't be able to survive the odd accidental submersion in water.
However, we found that the Galaxy S6 is the clear winner when it comes to build quality. Samsung claims that the metal used in the Galaxy S6 is 50 percent stronger than other high-end smartphone cases and meaning it won't bend.
Testing the two handsets we found some truth to this claim and the Galaxy S6 proved noticeably more mark and drop resistant than the Galaxy S5, which has metal coloured edges that are prone to chipping.
In terms of extras, the Galaxy S6 and Galaxy S5 both have fingerprint scanners built into the front home button and biometric heart sensors on the back.
The heart-rate monitor is designed to take advantage of fitness apps, while the fingerprint scanner lets users set the Galaxy S6 to unlock only after they have proved their identity.
Winner: The Galaxy S6
Display technology is an increasingly competitive area in the Android smartphone space as vendors race to increase pixel per inch densities to near farcical extremes.
The Galaxy S6 continues this trend and comes with a 5.1in, 2560x1440, 577ppi, Super Amoled touchscreen.
Samsung claims that the Galaxy S6's screen can display 70 percent more pixels than the Galaxy S5's 5.1in, 1920x1080, 432ppi, Super Amoled display.
Spotting disparities in resolutions that break the 400ppi count is always a tricky affair and this remained true when comparing the Galaxy S6 and Galaxy S5.
We noticed a slight difference in sharpness in the Galaxy S6's favour after a prolonged period of cycling through various test images, but it's negligible and most people won't notice it.
Brightness levels are also fairly similar, and the Galaxy S6 and Galaxy S5 both have maximum settings that are outright cornea scorching.
What most people will notice, however, is the huge difference in colour and greyscale levels. The Galaxy S5's screen was great when it was released, but colours now look oversaturated.
Comparing the Galaxy S6's display with the Galaxy S5, we found the difference in levels immediately obvious and the newer phone's display is noticeably better calibrated.
Whites appear cleaner than on the S5, which has a slightly greyish tone, and colours are noticeably more realistic and accurate.
Winner: The Galaxy S6
Next: Operating system and performance