In comparison to other Dungeons, Towers Dungeon was fairly middle of the pack. It had the highlights of all classic scenes, with a cast that was generally stronger than others as they had an existing pool of actors which they could select from, and generally stuck around longer. I never saw a half-arsed performance in it. However the theming was notably lacking, mostly due to it being a temporary attraction, there wasn't the same level of immersion or atmosphere, but it is rather impressive considering the whole attraction was built in six weeks!
It would have been interesting to see what was planned for the three extra rooms that got cut from the attraction, they were meant to be in the Lift building, with the lifts left in place presumably deliberately in case they ever wanted a 'Descent' scene or something similar. Expansions never happened not because the attraction initially wasn't successful, but because COVID hit and attention was focused elsewhere. Then when Trick O Treat Town came along, any possibility of expansion was left dead in the water and popularity dropped off outside of Scarefest because it simply wasn't fresh anymore.
The location was also a bit weird, because there really wasn't much foot traffic except for the corpse of Cloud Cuckoo Land and subsequently the World of David Walliams, where there was little overlap with audiences. It would have been better placed in an area of high foot traffic, such as in the Towers or nearby TowersStreet. Obviously Merlin leadership at the time wanted growth through the introduction of second-gate attractions and to replicate the success of Warwick Castle Dungeon. Still, without any integration with the Towers Ruins, it kind of just felt flat. Not to mention the Warwick Castle Dungeons is the only 'thrill' attraction there, whereas Towers Dungeon was competing for attention with the major coasters. Having it as an upcharge just put a load of people off.