My review can also be found at my blog, The Bookaholic: http://the-bookaholic.blogspot.com 
 I unfortunately have to rate Invisible Sun on the low side of the scale for myself--not because of terrible writing or a bad storyline, but simply because it wasn't in my tastes. It was on the younger side of the YA genre than I had initially expected (in my opinion from the writing style), and a sequel to boot that I was unaware of. This being said though, I didn't think it being the second book (the first book being titled "Black Hole Sun") affected my opinion. It made for a stand-alone and I wasn't really lost in the characters either. It even says before the first page that it can be read as a stand-alone without having read the first, so I didn't quite worry about it once I found out I mistakenly picked up a follow-up. 
 I do enjoy science fiction to a degree, but I'm insanely picky I guess you could say. When things get too high tech, or space fiction for me, it can start to be a bit of a turn off or almost dull on my end I'm sorry to say. I've never been into the space thing (in most cases). I even dislike Star Wars (oh the horror!). The writing in Invisible Sun was really solid, and I liked the witty-ness of the characters at times. However, this sci-fi tech space adventure was a little more juvenile than the books I tend to read and not quite my tastes. I would recommend it to anyone who enjoys the genres though--or who've read the first book and enjoyed it. I've seen some fantastic reviews on the first, and some recent good ones on Invisible Sun, so don't let mine deter your from your own opinions. Perhaps I would have liked it much better if I had read the first beforehand, and maybe one day I will. 
 Just not my usual style--but I still give it 2.5 stars for the unique and solid world building and interesting characterization. I did read it all the way through, so it managed to hold my attention that much at least and I appreciate the opportunity to read. 
 2.5 stars. 
 <3 
 Pixie