My family used the Hlads to renovate three bathrooms in their Carroll Gardens brownstone, 10 years ago. Since then, we always use them.
Just today (10/16/09), Joe Hlad and his son came by to repair a leak to a line in my steam heater that was flooding my unit and the people below me with a torrent of water. They quickly identified the problem by knocking through the wall, fixed the pipe, purged the boiler, and double-checked to make sure everything worked well before they left. The whole process took less than an hour. And then they rushed out to try to restore heat to 6 or 7 other people who called them with emergencies.
The Hlad family runs the most reliable plumbing business in Brooklyn (and we've used a lot of different people). Best of all, they're very nice. They go out of their way to do a good job, and have always called me to give an ETA of when they think they'll arrive. None better, in my experience and opinion.
(Apparently there is a disparaging review of them here on CitySearch, but the person writing it is clearly of substandard intelligence. Of course they make a mess. And of course, you MUST be present to supervise ANY contractor doing ANY work in your home or business, for communications' sake. That's just elementary.)
Pros: Longstanding reputation, reliable, kind
Cons: Very busy