I wasn't particularly impressed. For one, when Vince first arrived (which was on time) I asked about dirt and soot because I had heard stories about horrible messes and was told that was because "those other guys don't know what they're doing". On that basis, I took no steps to seal the rooms off from the rest of the house, cover our good furniture, etc. And my reward was several hours of cleaning a fine layer of black soot off our floors, walls, furniture, windowsills, etc. Our feet were black from walking around before the floors were washed. Second, while he spent quite a bit of time on the cleaning itself and I'm assuming it was thorough, he wrote all three of our chimneys off with a wave of his hand and little convincing explanation, telling us that it would take tens of thousands of dollars to make them usable. I couldn't help but feel like there was a great deal of arrogant exaggeration and that we were being upsold/gouged. On top of that, I sent a follow up email to get more details about what exactly was wrong with our chimneys, and received no reply. Will unfortunately not be calling them again.
UPDATE: Regarding the company's response below, the email response they refer to was received 3.5 months (i.e. two days ago) after my original email. This may have been a technical glitch but we certainly did not receive any follow up to find out why we had not replied. We had no subsequent conversation with Vince after he left our appointment and so could not have raised the soot problem in a conversation that did not occur. I'm not sure what a subsequent conversation would have achieved anyway since it would not change the fact that there was a considerable amount of soot residue that had to be cleaned up immediately and could have been avoided or minimized had an appropriate warning been given and additional precautions taken.
The email response to my inquiry, now that it has been received, was helpful in giving us specifics about what needed to be addressed but was materially different from what Vince told us during the appointment, when he suggested that repairs could cost $20K to $30K per fireplace, leaving us quite panicked.
My original review is factual and reflects our particular experience, which was less than we had hoped for. As I mentioned, we have no reason to believe that the actual cleaning itself was not thorough and well done. I hope this feedback is helpful and may improve someone else's experience in the future.