I've got a Droid 3...am about 50m away from 16 dbi 120 degree sector antenna running off a R52-300 card in a 433AH. I'm in a tent - nothing but other tents in the way. Getting two to three bars but only if I hold the phone up. If I put the phone down it looses connection and I have to log back into our hotspot. Whereas I have four bars on my netbook and no issues.
Think about the size of the antenna and the radio.
If I look at the Mikrotik and the registration page the cell phone gets between -70 and -76 and is running a 6 Mbps data rate. My netbook is running a -70 to -72 connection and is getting 11 Mbps.