Yeah... The New Adventures were impressively written, but they didn't feel that much like Doctor Who a lot of the time. It wasn't just that they were more adult, but that they were so dark and solemn. I liked how sophisticated and intelligent they were, but they weren't as much fun as the show.
I think I was lucky in the sense that I didn't read them to fill in for the loss of the show, and ended up exploring them piecemeal after their halfway point. I'll visit one I haven't read every once if I want a DW story that is more on the serious end of the scale. I think I read somewhere that the authors pushed the boundaries with the idea of the series having it's own identity, like how different TNG Star Trek is from TOS.
Yeah, McIntyre's Sulu was strangely gloomy. In Entropy, I figured it was just the result of the tragic events of the story and the life decisions he was faced with, but then he was just as sullen and insecure in Enterprise: The First Adventure, and it just didn't feel like Sulu.
I do like that she still gives a sense of him as a well rounded individual. I found the alternative depiction okay from the standpoint of it being an alternative version of Star Trek, inspired by the show and movies, but developing along a different path.