One inexplicable omission is Amazon Instant Video: the US version of the Streaming Stick supports it, but not the UK model. There's no ITV Player either. But even with that, there's more of the sort of content you are likely to want to watch on this Roku than there is on Apple TV, the Now TV box or Chromecast. There's still no cheap streaming box in the UK that can do everything, but this is as close as you can get right now.
Video and sound quality is decent. The Stick outputs at either 720p or 1080p resolution. It won't work with standard def TVs and because it's so small, there's no Ethernet port. If you have problems getting it connected to your router over Wi-Fi, perhaps because your TV is too far away or because there's other wireless interference, there's no hard-wired option to fall back on. If that's likely to cause you a problem, buy a Roku 3 instead.
An annoyance is that the Streaming Stick can be slow to load some channels. Ones like iPlayer, 4OD and Now TV load reasonably quickly, but Netflix and YouTube seem to take ages: somewhere around 30 seconds to get beyond the splash screen to the actual content. The Chromecast is much quicker at loading those last two apps, although it doesn't support the others at all.
One difference between the UK and US versions of the Stick is that there's no search function on the UK version. That's a shame: US reviewers generally love the fact that Roku's universal search looks for the show you want across all the services, rather than requiring you to run separate searches in each channel. But such is life.
I am still searching for the perfect TV streaming box. The Roku Streaming Stick isn't it, but it's as close as you can get for now. It supports lots of UK channels, if not all, and what it loses in sometimes slow loading times, it makes up for in ease of use.
It certainly makes the Apple TV look like a relatively poor buy: at double the price and with no iPlayer support, it's currently not a great choice for most in the UK. The Now TV box (which is a cut-down Roku box anyway) is a cheaper alternative, although there's no YouTube or Netflix there, with the Chromecast remaining the cheap choice for anyone buying their TV and movies through Google.
I wish Roku had released a slightly more polished product that better reflected what the Streaming Stick is capable of in the US, with universal search and support for Amazon Instant Video. But for just £50, it's still a good buy.