I passed up on this game because of the negative reviews. That was my loss.
If you like your Total War game to have:
Over-powered agents
One man army single entity commanders
Over-powered unit special abilities
Absurd composition of AI armies
Repetitive battles because the AI is able to spawn new armies turn after turn
Battles, the outcome of which is primarily dependent on the rate you can point and click a mouse button

Then this is NOT the game for you.

If, on the other hand, you are looking for a historic Total War title, that has none of the features above, has probably the best siege battles in the series, has a recruitment mechanic that results in diverse and balanced AI armies. Then this may be the game you are looking for. Pick it up in the sale for the price of two coffees.

great game if you enjoy hitting the end turn button over and over while nothing happens.

Slow and tedious, its a shame because I love this era in history but if you want a decent Medieval Total War Britannia entry stick to Medieval 2, which feels ridiculous to say but the 15yr older game is just a better game