After re-soldering two boards on a hot plate I got one working in I2C mode. The SA0 pin is not soldered correctly, but the internal pull-up is doing its job so I can communicate with the chip at address 0b0011001:

• An I2C scan shows that the device ACKs its slave address;
• adafruit's LIS3DH library reports correct values for x, y and z acceleration when I tilt the breadboard;
• my own code that reads the WHO_AM_I register reads back the correct value (0x33).

I'm now waiting for the revised boards to arrive from OSHPark to see if I can solder them with paste in #vapsy

So far this has been the hardest chip I ever had to solder. If you don't
need to mount this on a custom PCB, go for a ready-made breakout board
(this advice might change, or not, when I tested the new layout).