Samsung unveiled its Galaxy S6 and S6 Edge phones at the Mobile World Congress this weekend, but they may not be enough to unseat the Apple iPhone 6 Plus in a mobile phone popularity contest.

The Galaxy S6 Edge features a curved screen, which Samsung said will create a more "immersive experience." Others are less taken by the screen.

"The curved edged screen is a gimmicky parlor trick," said Shelly Palmer, managing director of the digital media group at investment bank Landmark Ventures. "They got rid of the removable battery, which was the best feature of the phone," Palmer added.

Mark Spoonauer, editor in chief of Tom's Guide, also criticized the lack of a removable battery, but he lauded the Edge's screen.

"I love the way that they've put Gorilla Glass on the back and it reflects the light, so it seems like it's changing colors," Spoonauer told CNBC.

Read MoreSamsung unveils curved Galaxy S6 Edge, payments

The iPhone 6 and iPhone 6 Plus helped Apple beat out Android's share of the market for mobile operating systems, though by a slim margin, according to technology research firm Kantar Worldpanel. In December, iOS owned 47.7 percent of the smartphone operating system market, while Android took 47.6 percent of the market, according to the firm's research.

Samsung's new phones will be available worldwide on April 10, the company said.

Both Galaxy S6 phones will come with wireless charging technology built in, according to Samsung.

Watch: With S6, Samsung still faces 'uphill task': IDC

In terms of hardware running the Android operating system, the Galaxy S6 will compete closely with the HTC One M9, but each have their pros and cons.

For example, while the Samsung phone has a screen resolution of 2560 x 1440, the HTC phone shows 1920 x 1080.

Watch: Good design, but can Samsung's S6 beat iPhone 6?

And while the Samsung phone no longer has expandable storage, as previous Galaxy models have, the HTC phone's storage space is expandable with a microSD card slot, according to company specifications.