I've used them, my payouts have been slow taking about 3-4 weeks to receive a check, they are reliable so you will get paid.
Lines aren't as good, fav spreads will be higher than a book like 5dimes, who I think can't be beat for the flexibility of lines (if a spread is -3, 5dimes also offers -2.5, -2, -3.5 with different juice, for example) and variety of props and other wagers such as half and quarter lines.
Bookmaker's best feature for me is their mobile app which you can download to your cell, i don't know another book that offers that, makes it very easy to place a wager on your mobile device if you're not near a computer (or you're at work and you can't use the company's computer!), a big convenience if you need that sort of thing.