All right guys here's the real deal from someone actually in the auto glass biz......
Windshield repair regardless who does it is nothing more than a crap shoot, more crap than shooting though.
In 1988 I bought a Novus Windshield Repair franchise---it wasn't all the effective then and its not advanced one bit since.
When a rock chip grows into a crack that travels the full width or height of the windshield there is absolutely no danger of it falling in your lap or otherwise rendering your vehicle unusable. You or your passengers won't be impaled, beheaded or any other such nonsense. Windshields are two pieces of glass with an inner lamination very much UNLIKE typical plate or tempered glass found around the home. Look at any vehicle involved in a collision, even those with severe front damage --notice how the windshield is still intact?
Not to further derail this topic but windshield installation is subject to several Federal Motor Vehicle Safety Standards. While never failure proof that should give a small bit of piece of mind a cracked windshield isn't a major safety risk.
Of course Safelite's TV and radio commercials lead the unsuspecting to believe they're in mortal danger and only they can do a 100% restoration to pre-chip or break condition including their claimed "vehicle structural integrity". (If there was ever a case of false and misleading advertising this and several other of their advertisements need to be reviewed!)
There are many many DIY windshield repair kits available and they're just as effective as the services most glass shops offer. For $10-12 per kit you've got the same process and results.
IF you're in need of a windshield replacement ask your potential installer what brand they use or have available. Brands such as PGW (formerly PPG), Pilkington, Guardian are the pre-eminent brands and DO NOT carry a premium installed price--they all tend to cost glass companies the same dollar amount----be aware of this.
The glut of Chinese and other low quality crap on the market such as Safelite manufactures and pushes has greatly changed the auto glass biz and not for the better. Unless someone gives you a lifetime warranty of 100% usability you're taking a chance with receiving a poor product that's not as much a bargain as it seems at first.
Anyway aren't you glad you asked?