Following the F1 and the F1 Plus, we now have the F1s from OPPO, completing the trilogy of photography-oriented phones. Where the F1 Plus was a noticeable leap ahead of the F1, the F1s' position is somewhere in the middle. On the face of it, it's hard to tell it apart from the F1 Plus.

Indeed, with both the F1s and Plus on my desk side by side, it's impossible to know which is which except if you're looking at specific things — not necessarily a bad thing, since the F1 Plus is a nice piece of hardware. The new F1s is a little larger, a little less powerful, and is making its debut in India for ₹17,999 ($270).

OPPO (the parent company of OnePlus) has suddenly become one of the world's top five smartphone vendors, so it's very much a company to follow. The F1s isn't particularly different from its predecessors, which means it has the same good and bad points that we've come across before.

Externally, the F1s looks a whole lot like the F1 Plus, but with subtle differences that give it an aesthetic advantage. The ugly antenna lines from the Plus are gone and what is left is a metal back with only the thinnest of breaks. This is likely due to the addition of plastic cutouts on top and bottom, but either way, it's a more attractive chassis. The camera flash is now to the side of the lens, and while the design tweaks are minimal, what you get is an overall better look.

Round the front you're looking at a 5.5-inch 720p LCD display with a physical home button beneath that doubles as the fingerprint sensor. And once again, OPPO nailed this. The fingerprint scanner on the F1s is crazy fast.

As usual OPPO did a nice job on the display as well. 720p isn't the highest resolution for this size, but it looks really good. It's visible in fairly bright sunlight and has the eye-protecting blue light filter mode built in that I'm now so attached to. OPPO went away from the AMOLED in the F1 Plus, no doubts to bring the price down a little, but it's still great to look at, even side-by-side with the Plus. Colors are noticeably different to the AMOLED, but whites have a cooler tint, which I personally prefer.

What will split opinions is that the F1s comes pre-dressed with a factory fitted screen protector. Love it or hate it, it's there. It's also there to peel off if such things disgust you. Oh, and while the back of the F1s is metal, the sides are plastic simply painted to match. But as with the F1 Plus, the F1s is sleek, slim and generally a pretty good looking product.

You still get microSD support from OPPO, which will please folks who like that sort of thing, but you also get a decent amount of internal storage. Not as much as on the F1 Plus's 64GB, but 32GB is a great starting point that I wish more companies used.

Hardware isn't really OPPO's problem, and this latest "Selfie Expert" phone isn't breaking from that form. Where we usually find fault is when you turn it on and see the mess that is Color OS. Most disappointing is that OPPO has been teasing the stock-ish looking Project Spectrum for what seems like an eternity, but Color OS still prevails.

The issue isn't even what it looks like anymore, nor, thankfully, its overall performance. Color OS used to be pretty appalling in both areas but with version 3.0 big changes were made. There's a much flatter, brighter appearance nowadays and it's super smooth and snappy to use. But it's still based on Android 5.1 Lollipop, and with Android 7.0 on the horizon that's simply unacceptable.

In China, the version of Android might not be an issue. But even though the F1s isn't slated for a North American or European launch, it will be sold in markets where people do care about this stuff. OPPO is now one of the big boys, and it absolutely has to up its software game.

If you want a more in-depth look then check out our review of the F1 Plus, which tells pretty much the same software story. Same good bits, same bad bits. Same Lollipop. That last one gives us the biggest sad face.

Bouncing back to things that are better to talk about: cameras. You've got the same basic set up on the F1s as on the F1 Plus, in that there's a honking great 16MP front-facing camera on the front and a 13MP shooter on the back. And as always, megapixels don't tell the whole story. You simply take amazing selfies with this thing.

Marketing buzzwords aside, if you're fond of using a front facing camera then the OPPO is worth your attention. It won't make you truly beautiful — much to my dismay — but it'll make your self portraits look sharper than many a phone out there. The camera app is super simple to use and still looks like the one you'd find on an iPhone, but it's the results that really matter.

And while the F1s won't win any best-in-show awards, it has a competent rear camera, too. I took the F1 Plus on a trip to China while reviewing it and was pleasantly surprised at its speed, ease of use and image quality. It's the same story with the F1s, much to my delight.

You'll get a decent day's use out of the F1s, too, with a fairly sizeable 3,075mAh battery squeezed into its svelte frame. OPPO's way of displaying battery usage stats to its users is still a mess, but you're probably OK to ignore it throughout the day, anyway. The VOOC fast charger is also included in the box, offering you the chance of a quick top-up should you need it.

So, final thoughts. We haven't gone as in depth with the F1s as we might have other phones, because for the most part you could read our F1 Plus review and get the general idea. The F1s is one of OPPO's best phones to date, but the software still drags it down from becoming a truly great phone.

OPPO isn't alone on that front, and heaven knows we've been saying it about other Chinese phone makers for long enough now. What's currently here works just fine in China, but other parts of the world are going to want to see newer versions, the up-to-date security features and regular progress in keeping phones updated. OPPO is doing a lot right, but it needs to get this part nailed.

The F1s also does a lot of things well. It's up for sale in markets such as India and, software aside, is a very nice phone. Hell, even the software it's got is okay — it's just dreadfully out of date. Fix that, and you've got a lot of phone for not a whole lot of money.

Interested? The phone will be available starting August 11 for ₹17,999 from Amazon India as well as brick-and-mortar stores across the country.