Ruby Red combines three things I'm usually sceptical about: 1. It's a bestselling novel. 2. It's a novel about time travelling. 3. Romance is an important part of it.
But I was positively surprised that it was so well and funny written. It made me smile quite often. It was also quite exciting and made me want to read on and on. So if I just consider the writing and that I had a great time, I'd rate it 5 stars.
However, there is a huge BUT: the end of the book wasn't really an end. I know that Ruby Red is part of a trilogy but you just can't let a book end like that. A book can end with a cliffhanger, that's perfectly fine. But this wasn't even a real cliffhanger. It felt more like, "Oh well, I don't know what to write now so we'll just leave the story as it is and I'll think of the rest at a later point". But that doesn't work for the first part of a trilogy/series. It's ok for a later part when the reader already knows a lot about what is going on and is just waiting for the great final.
I'm really looking forward to reading the next part which will hopefully give a few more explanations (and not such an abrupt end).