I can't recommend Magoosh highly enough. I was extremely nervous about the GMAT after having barely touched math since high school. I was starting from scratch. The lessons were invaluable in explaining the concepts in a clear manner. The hundreds of practice problems are amazing for letting you practice under time pressure while adjusting your difficulty or focusing on specific problem types. Every problem has a video and text solution and allows you to take leave notes for yourself when you review later. I didn't really need help with the verbal but still managed to pick up some good tricks help me improve my CR scores.
After 5 months of prep, I finally took the GMAT and did much better than expected with a 740. I ended up waitlisted and decided to retake it to improve my quant score. I paid for another round of Magoosh premium and focused solely on the problems (along with the GMAT Official Guide and the Manhattan Advanced Supplement). After 5 weeks of studying, I bumped my quant score another 3 points.
For the price it really can't be beat. One downside - their iOS apps are pretty weak. The website is still fairly functional on mobile but not the greatest whenever you have longer text passages. The scrolling gets a bit screwy. Not a big enough deal to make a difference in my opinion.