Blindsense is a lesser ability that lets a creature notice things it can not see, but without the precision of Blindsight. The creature with Blindsense usually does not need to make Spot or Listen checks to notice and locate creatures within range of its Blindsense ability, provided that it has line of effect to that creature.
Any opponent the creature can not see has total concealment (50% miss chance) against the creature with Blindsense, and the Blindsensing creature still has the normal miss chance when attacking foes that have concealment.
Visibility still affects the movement of a creature with Blindsense.
A creature with Blindsense is still denied its Deterity bonus to Armour class against attacks from creatures it can not see.
Based on the entry in Dungeon Master's Guide 3.5 Page 291.