If you're serious (read: anal) about espresso, you need shot glasses, and these are the ones you need.
Positive Product Points
Solid weight, 1.5 ounce size (with 1 ounce line), most important feature - the line hasn't worn off yet!
Negative Product Points
None... these are nearly perfect. I suppose a nice 1/8th ounce set of calibrated lines would have been nice.
One thing I use up a lot are shot glasses. I do product shots of espresso pulls, and I like pulling into shot glasses because it shows the crema formation and the "guinness effect".
I say I use up a lot of shot glasses because I try to keep them crystal clear - it makes it easier to take good pictures. Because of this, every shot glass I've used has had the lines and indicators rub off. And one shot glass I used actually broke from the heat of the espresso shot!
But now I no longer go through them - I have been using the same shot glass for the past 5 months - a pair of them that I bought from www.espressosupply.com for around $3. These are 1.5 ounce glasses to the rim, with a 1 ounce marking line that is very accurate - the line is the thickness of water's miniscus at room temperature. They are solid, very well made, and suit the job I've given them perfectly. I've probably used them about 4 dozen times so far, and still the lines look as good as the day I bought them.