Remember the story? Sarai was upset that Hagar was pregnant (Go figure, Sarai. Wasn't that your idea?), so she mistreated her and Hagar ran into the desert. Alone and discouraged, God found her and told her to go back to Abram and Sarai. Ishmael would be her son. In response, she said, "You are the God who sees" -- El Roi.
The term has positive and negative connotations. She was awed that God found her where she was. She was awed that He promised to take care of her, that He saw her and cared about her and her unborn baby. Positives, all. And she was amazed because she had remained alive.
A similar concept is found in Psalm 139.
You know when I sit down and when I rise up; You understand my thought from afar. You scrutinize my path and my lying down, And are intimately acquainted with all my ways. Even before there is a word on my tongue, Behold, O LORD, You know it all (Psa 139:2-4).David sees this as "too wonderful" (Psa 139:6). That the God of the universe would be watching me that closely is truly wonderful.
Of course, unless you're perfect, you can also see the ominous side of "the God who Sees". He sees what you do wrong as well. We've heard "God is always watching you" as a means of deterring sin, but we rarely really think about that. Perhaps we ought.
Why is it one of my favorites? I tend to think of God as transcendent, as far above, as "something other". He's really ... out there, so far above me that I can barely even perceive Him. This title, "the God who Sees", brings back the immanence of God. He's not only "out there". He's right here. He is indeed concerned about the here and now, a God who sees me. It's an intimacy I need. And what about that negative factor knowing that He's watching when I sin as well? Well, I can really use that, too. That is a good thing. Win-win! Yes, one of my favorites indeed.