So, from the very first seconds you see what the filmmakers are going with it... and failing miserably. In case you didn't pick up on the 'cheeky bandit' lead and the soundtrack, fast cut editing helps you realise that it's not a historical drama about Robin Hood - it's an adventure movie with elements of comedy - that totally rely on the lead's charisma - but set in period costumes (ish).
The failed Jack Sparrow with a bow (which we don't even see him use that often) is... pretty boring. To be able to make the audiences interested in a historical film with a 'modern touch' (meaning editing, special effects and other quirky things that remind you that it's supposed to be a blockbuster movie and not a story as such), you have to have a very, very good script, plot or main lead. Since the plot doesn't really matter (which is pretty obvious - there is none, judging by the trailer), one can expect it to be compensated by the character design. Well...
The lead actor looks plain boring and not nearly as charismatic as the trailer wants us to think. Other characters' phrases imply that we share their familiarity with him - oh it's that cool cheeky guy who steals from the rich and gets a kick out of it... But we don't. What we see is a young cocky man without a purpose, no common sense and not even a good sense of humour (so far). And although Taron Egerton is trying really hard that he is a new funny rogue hero, and although he might be doing it right by the books - that's just not enough to live up to the expectations lazily thrown at him by the scriptwriters and the director.
Is there anything else that could have made this film interesting, apart from a cool adventurous plot and a compelling hero? Probably not - at least not for the type of film Robin Hood is being marketed at.
As a result, the trailer does the film more harm than good - you're not even curious to see if they make it work, as is the case with Mary, Queen of Scots. How can it?