It was alright. The disjointed flashback/current event structure didn't work as well for this movie as I would have liked, and the flashbacks to what Arthur is supposed to "understand" over and over again was pure tedium. The plot got a little melodramatic in places and just wasn't all that strong to begin with as far as versions of the King Arthur story go.
The action was also very eh, heavily marred by CGI use and some desire to emulate 300's combat but do it worse. Still one of the more enjoyable aspects of the movie, but toning down effects and prioritizing more fluid choreography would have gone a long way towards making it truly a redeeming feature even if the rest of the movie was lacking.
It certainly wasn't awful by any means, but it was entertaining. Good enough for a watch that will be called "okay" at the end.