File formats support is good -- it plays a range of Xvid and MKV videos. The fast forward and rewind controls don't work on MKV files if you're streaming them over a network however. Very annoying.
Next up is the Social page. If you enter your details for services like Facebook and Twitter you'll see videos listed here that your mates have shared from YouTube and other video services.
The final screen is for Apps, which is where you'll find all the main catch up TV apps. Samsung's range of catch up TV apps is excellent, with iPlayer, 4oD, ITV Player and Demand5. It also has apps for Netflix and Lovefilm and there are premium movie rental options, such as KnowHow movies. It all helps to make this the best smart TV platform out there at the moment.
The F6800 makes do with two 10W down firing speakers and doesn't have the mini woofer on the rear that you get on the company's high-ends sets. This does compromise its audio performance slightly as it lacks weight in the bass department -- bass sounds boxy and cramped rather than boomy. Its mid-range performance isn't bad though, which helps it to deliver fairly clean sounding voices in movies and TV shows. Certainly there are better sounding TVs on the market -- Sony and Philips models generally perform better on the audio front -- but this Samsung doesn't disgrace itself.
2D picture quality
Samsung's picture presets on its LED TVs have never been great and the four you have to choose from here -- Standard, Natural, Dynamic and Movie -- aren't wonderful either. Movie is the best of these, but even with this one there's too much picture processing turned on by default.
It's a good idea to tone down or turn off the motion processing when watching films as otherwise the set gives them a glassy look. I found it was best to turn off the de-judder setting in the Motion Plus menu and keep the de-blur slider at around the three mark. The F6800 is a reasonably good performer when it comes to motion anyway -- by LED standards at least -- so it doesn't need the aggressive processing Samsung uses.
On the whole, black levels are very good for a model at this price. There's still some clouding in the corners of the screen when you're viewing in a darker room, but you can reduce this by lowering the intensity of the backlight. This does rob the picture of some punch, but the F6800 pumps out a lot of brightness anyway so it's not a huge sacrifice.
Colour performance is another strong point, as across both standard definition and HD pictures colours look warm and rich with subtle hues deftly handled.
Like many TVs that use Vertical Alignment LCD panels, its deeper black levels come at the expense of good off-axis viewing -- if you're looking at this TV from a more side-on angle, colours tend to take on a blue-ish tone and the screen looks darker than if you were sitting right in front of it. Its upscaling engine also doesn't work as well as the one in Sony's comparably priced TVs, so standard definition channels on Freeview can look slightly soft, especially if they're heavily compressed, such as 5USA.
Overall though, the F6800 puts in impressive picture quality for the price, with it's slightly deeper black levels and motion clarity making it worth the slight premium over the F6400.
3D picture quality
Samsung is holding out against the tsunami of LED sets that use passive 3D and sticking with active 3D instead. This means it relies on the more expensive active shutter glasses. Two pairs are included in the box, which are powered by watch-style batteries. They feel flimsy, but are at least lighter than many other active 3D specs, and you can see flickering from any ambient lighting in the room, which can be tiresome on your eyes.
On the plus side, the glasses produce a Full HD 3D image, so you don't get the stepping on edges that you sometimes see on passive 3D displays (apart from 4K ones, that is). The F6800 has plenty of brightness on tap, so even with the glasses on, images look perky.
Thankfully the F6800 manages to avoid most problems with crosstalk. Some creeps in now and again, but it's very subtle and you have to look for it to really see it. Overall, this is a good TV for 3D viewing.
Although its picture quality isn't quite as good as Sony's KDL-40W905A, the UE40F6800 is substantially cheaper and has a much better smart TV system. It also outclasses LG's similarly priced LA740, both in terms of picture quality and smart TV apps. As a result I think the UE40F6800 is a great option for a family TV, simply because it offers such a good compromise between price, features and picture quality.