I've had great success with this module. Wonderfully robust signal and has been very reliable.

PUBLIC SERVICE ANNOUNCEMENT: THIS UNIT WILL NOT WORK AT AN ALTITUDE OVER 18000 METERS (60000 FEET)
THIS UNIT WILL NOT WORK AT AN ALTITUDE OVER 18000 METERS (60000 FEET). This doesn't matter to most people, but is important to hobbyists that take part in high altitude weather ballooning, amateur rocketry, etc. Someone I know mistakenly purchased a unit with a similar limit for ballooning and I'm hoping to save people from making the same mistake.
I'm going to post this in the comments section of all similarly limited Sparkfun GPS products in the hope of saving someone from from making the same mistake. I apologize if the Sparkfun guys consider this spamming, that isn't my intent. It, also, isn't my intent to drive business away from Sparkfun. They have an awesome collection of GPS products and many of the other modules don't have this limitation.

Excellent piece. Started with no external programming required. Did have to make a TTL converter from IC3232(3.3v) to RS232. Worked perfect with computer mapping set at 4800 NMEA. First fix took several mins. Cold start takes about 1min, memory battery didn't seem to decrease this time any.
Caution! Use extreme care with the antenna mounting on this unit. The antenna isn't mounted/glued/attached very well. Only secured by two nano solder joints on board. I had to take the little shield off and repair nano circuit traces and capacitor that had broken off with very little pressure. Unsure of the value of cap but soldered in .1uf and unit works again. If possible glue the back side(opposite the logo) were white antenna mounting tab attaches to board and solder a brace from shield to shield. If you mount this through a case with ABS shield for antenna it will put a lot of stress on the circuit board if not secured really well to case.

Basically, it works. The specs are perhaps a little optimistic. The physical dimensions are right on, and the power consumption is Ok at 70-90 mA. The time to acquire a fix is considerably longer that specified (several minutes is typical). But given enough time it locks on and gives an accurate 3D fix. It helps significantly to have the antenna in a vertical orientation. It responds to SiRF commands, which are not documented here but can be found easily enough by searching the web. Don?t forget to purchase the connector with this unit; otherwise it?s near impossible to connect wires to it. So overall, I?m satisfied.