Oppo skipped three numbers with its latest R15 and R15 Pro smartphones, which follow the R11 line released last December.

The Chinese smartphone manufacturer has given no explanation for this bizarre naming convention, but do not expect the flagship duo to leap ahead by four iterations.

The Oppo R15 line is the best smartphone for iPhone fans who do not want an iPhone X, for whatever reason. It features a near bezel-less look, a notch on the display and, well, a price tag higher than those of other phones in its category.

But unlike the iPhone X's top-tier specs, the R15 and R15 Pro feature solidly mid-tier performance in high-end cases.

Both phones look virtually identical, with the Pro a smidge - 0.2mm - longer, which is barely noticeable unless you place both phones side by side and eyeball them hard.

One difference is in the processor, with the regular R15 opting for a chipset from Taiwanese manufacturer MediaTek, while the Pro packs a more familiar Qualcomm Snapdragon 660 processor.

The R15 Pro also has a smaller battery than the R15, possibly due to the different chipset used. Battery life is fair to good, with both phones lasting an entire day with moderate use.

The other significant difference lies in the rear camera set-up. The R15 has a 16-megapixel (MP) main camera and 5MP secondary one, while the Pro has the same 16MP main camera and ups the secondary camera to 20MP.

Both phones have the same 20MP front-facing camera - a legacy of Oppo's niche in the selfie-taking crowd.

On auto mode, both phones take similar-looking photos, with good detail and colour and quick performance. Nothing stands out, but nothing falls flat either. The R15 phones are perfectly serviceable shooters with a variety of options, from slow-mo to time-lapse to portrait modes with various filters.

However, the secondary cameras in both phones are neither a telephoto nor a wide-angle lens and serve to provide just more depth details for portrait shots.

The difference in portrait quality will be the main deciding factor in going for the cheaper R15 or the pricier R15 Pro. The R15 Pro takes softer, more pleasing portrait shots that look more natural than those of the R15.

To Oppo's credit, the R15 line does make some standout design choices, with the phones boasting bold, vibrant colours.

The large screen estate and minimal bezel also make for a great viewing experience.

The R15 phones run Oppo's own ColorOS, a modified skin of Android 8.1.

This skin makes the phone look and feel more like an Apple device, including the gesture controls found on the iPhone X.

I found the action of swiping to navigate much more tedious than simply tapping on the navigation buttons, but it does provide just that little bit more screen estate.

As with any mid-range phone, you make some sacrifices with the R15 line. There is notably no dust or water resistance and both phones come with a microUSB port, instead of USB type-C.

It is hard to justify the R15 and R15 Pro's respective $749 and $899 price tags when serious contenders, such as Huawei's $579 Honor 10 and the $599 Nokia 7 Plus, offer similar specs and performance at a much lower price point.

• Verdict: Oppo's R15 and R15 Pro mark another step in the company's ambitious plans to make its mid-tier flagships stand out as premium products, but the phones' mid-range specs do not justify their high price. Their design and camera capabilities, however, appeal as stylish lifestyle products.