First person interpretation (i.e. a living, breathing, human guide) at its best is what all other interpretation aspires to be: personal, intimate, detailed, tailored to fit individual needs and interests.
The guide at Glebe House (to my sorrow I've forgotten her name) was wonderful. Warm, personable, clearly both knowledgeable and enthusiastic about her subject. It helped that she had known Derek Hill and so was able to act as a link between him and us, telling us anecdotes about him and the people who had visited him.
Contrast that with a recent experience I had visiting a National Trust property. The guide reeled off from what was clearly a prepared script (I have no issue with scripts, I've used them myself, but you shouldn't sound as though you're reciting from one) displaying absolutely zero enthusiasm for the house or the history it represents. The lowest point was when the guide referred, several times, to a wealthy 'higher-ess' who had revived the family fortunes. I promise this is not a dig at the pronunciation - just that it was symptomatic of a general 'can't be bothered' attitude. She seemed bored - and in consequence the tour was boring.