Pros
I have worked for headwire for a total of 6 years and I'm quite honestly surprised by some of the unfavorable reviews. As a seasoned consultant and Software Architect I have worked for several Fortune 500 consulting firms and believe that headwire is the only consulting/engineering shop where you can work with great clients on interesting projects while maintaining work-life balance. Every other consulting company and/or agency I have worked for claim that they offer work-life balance, but that was rarely the case. In my experience, headwire actually delivers on the right mix of work while allowing you to enjoy life. Their "flex hours" make it easy to take care of personal tasks through out the work week. In addition to the flexible hours, you are actually required to maintain a work schedule that rarely exceeds a 40-hour week (with the exception of the occasional "launch weekend"). Unlike the traditional consulting "road warrior," travel is near minimal (unless that's something you express interest in doing). In my time at headwire, I have been blessed to be mentored by the CTO, work on personal projects, contribute to a number of open source projects, design and build large scale web sites for amazing brands, speak at industry conferences, and most importantly--live life while building a career.
Cons
The only con is the steep learning curve to master some of the non-mainstream technologies used on most projects. headwire is largely focused on delivering large scale sites built on Adobe Experience Manager (AEM). It may take some time to become comfortable with AEM's underlying technologies (e.g. OSGi, Apache Sling and Jackrabbit Oak). Honestly, if you have a passion for software engineering, this is actually a pro. Not to mention this space is hot and pays well.