The Parallax servo is pretty good if you're lazy and don't want to modify servos yourself, especially if you need to use 4 or 6 on a robot. Adjusting them is a real snap compared to the regular kind, since the pot is accessible without opening the case, and so you can use it with a micro (exactly 1500us center) or a RC set (which usually have a center off of 1500us for some reason).
The actual mechanicals of the servo are nothing out of the ordinary.
The connector is an "universal" type, but the output shaft is Futaba-style (it's made by Futaba), so it won't fit into Hitec-style servo horns/wheels.
However, like modified servos, the pot adjustment does drift a little if your bot goes through a rough trip to a competition or something. Like normal motors though, you can fix that with a bit of hot glue.
I'd recommend them just because they're easy to adjust. I hate having to take a servo apart after it's mounted on the inside of a robot.