I tried to be open minded and had a low expectation, even so I was bitterly disappointed. I decided to try it out after watching series 1-7 of Death in Paradise on Netflix and hoped to dine series 8. No such luck, it seems the BBC hold on to the streaming rights for 12 months for their iPlayer. Which would be fine, but DiP is not there either. To make matters worse there are other BBC shows that are absent, in fact I searched for several shows and couldn't find any of them, Next of Kin, It ain't half hot mum and The last train! What annoys me the most is that if you search for a show on Netflix that they don't have, Netflix shows suggestions for alternatives that you may like based on your search. The other annoyance is that most of what is available on Britbox is also available on free to view streamers and/or Sky box sets. The 'Carry on collection' is far from complete and there are more available on the ITV hub than Britbox.
In short there are bound to be a few people who will benefit from Britbox, people who do not subscribe to Sky, Netflix or Amazon Prime and have one of the very few devices that the app support, but for the other 95% of the U. K. Market I suggest you save the time and money and just sign up to UKTV play instead, it's free and has a lot of the same thing as Britbox.