In law school, you'll hear a saying: "reasonable minds can--and often do--differ." If there were ever a case of reasonable minds being in disagreement, it would certainly be over Loki.
I present for consideration a few thoughts on Loki. They are by necessity incomplete--Loki has so many aspects and faces. All of the Gods and Goddess are delightfully, upliftingly complex--complex enough to nourish a worshiper through a lifetime and beyond--but Loki carries this especially far.
I'm not, strictly speaking, a dedicant of His (or whatever word might best apply). However, He's unquestionably the God I'm second-closest to. He is very much a friend. The Christian-influenced Prose Edda aside, we do have some positive sources on Loki, e.g., the Lincolnshire Hammer Charm and the Lokka Tattur Ballad.
The Lokka Tattur is a good place to start. In it, Loki goes out of His way to save a child from being devoured by a giant when two other Gods had given up on the task. One of the strong personal impressions I have of Loki is as a real protector of the innocent, especially children and animals. He's a prankster--very much so--but not a God of wanton cruelty.
Another way I've experienced Loki is as a God of the Shadows--or of the "Shadow," in the Jungian sense of the word (and here I'll quickly recommend "Why Good People Do Bad Things" by James Hollis. It's an excellent read, and the author quite forthrightly acknowledges the advantages of polytheism). If you're willing to set aside fear, to make the attempt to get to know and trust Loki, the rewards are immense. On so many levels, He is a God that brings great treasures.
On a similar note, He is a God for the outsider, for the ones who don't fit in and aren't willing to "fake it" to do so. Loki crosses boundaries of every sort (even stepping outside His own pantheon... I've met at least one genuine Lokean who does not worship any other Norse Gods).
He's a very honest God. Be careful with your expectations around Him: He might well oblige them. He's the God of "don't be an idiot" and He reserves the right to prank you if you do insist on being one. But He's also very understanding and compassionate in His way. He gets the hardest parts of being human. Knowing Him can be profoundly healing, sometimes when you didn't even consciously realize something was wrong. My closest God refers me to Him periodically. There's no conflict there. Our Gods are grander than preconceptions.
On the subject of healing, Loki is the God of heartfelt laughter and a good story. What restores the spirit like a good tale? What brightens up the day like an honest laugh? He's the center--the catalyst--of so many of our very best stories.
Like Odin, Loki is also a God of shamanism. The introduction to Kevin Crossley-Holland's "The Norse Myths" has a great discussion on this. Dreams, shapeshifting, and meditation are all things that He is very good with. This is how I met Him--first, in a dream. Later, He introduced me to His friends.
I owe Loki in the most profound way. He's the God who guided me Home. While being respectful of the fact that everyone's experiences vary--that reasonable minds can and do differ--I feel that it is important to be honest about what He has done for me and to gently state the other side of His case when the circumstances are conducive to doing so.