Ok, disclaimer, because I'm sure it will be an unpopular opinion, but I DID actually enjoy it. There were just a lot of little things that bugged me. I was never a huge fan of Lucinda Riley's writing, and I'm not sure which parts of this were hers and which were her son's, but I'm really not a fan of the dialogue. I hate how often the characters call each other "my love". It rings false and I don't know anyone who actually talks like that. There are also a few grammatical errors/word choice errors, and I admit that those really bother me. It's just not a writing style I like. BUT, I do like the stories, which is why I kept reading after the first one.
I also feel like it goes a BIT over the top. I like that all the loose ends are tied up by the end, and I was right about one major plot point that I won't spoil for other readers. But overall, it was just a bit too.....too. Just the basic premise of a young boy making it that far on his own without anyone who he encountered having contacted authorities....it doesn't make sense. Perhaps in an earlier century when the world wasn't as populated and when children had a lot more responsibilities at a young age, a boy might have escaped notice. But in the time period in which this is set, with big cities and complex transportation systems, I don't think it's that plausible. There are a few other things that would be spoilers, that are a bit over the top. I can ignore most of it for the sake of the story, but as a whole, because there are so many of those things, it does bother me slightly.
That all being said, I do like the overall story line. I like the suspense, and most of the characters, and I like how things are left at the end. (I actually laughed out loud right at the end and my daughter wondered what I was laughing about.) I think it will satisfy most readers who have stuck through the whole series. I also found it to be a relatively fast and easy read, so I think it is a good one for anyone who has never read such big series before, as long as they like the genres. If you don't like historical fiction, romance, or suspense, these aren't going to be your thing. I like that the whole series encompasses several different genres because I like the variety. But if you don't like overlapping genres, this isn't going to be your thing.
While all the books are very thick, they aren't difficult to get through. There's no real difficult language or anything, but I'd advise people to maybe try the first one through a library to see if you like it and it's worth investing in the others before getting the whole series based on its popularity.