I won't lie - Messiaen is not necessarily easy to encounter at first. I had trouble sorting out what was going on myself until I listened to many of his different works and got to understand his style, and also read about what his goals were in composition.
So, at our college they will perform the
Oiseaux...which doesn't include my instrument, so I get to watch instead of play. My friends playing are passing around a recording, for most of the people playing this is perhaps their first encounter with Messiaen. And when they put headphones to the ear, there are some rather shocked and horrified faces! Besides it being a difficult piece, they just have trouble finding understandable music in it to grasp onto.
I wonder if after the rehearsal process, where they'll really get to know the piece and more about Messiaen, if they'll come to like it a bit - I think maybe, they will.
Humor is definitely a big element, and just general quirkiness....there are these often irreverent and somehow wandering percussion and woodwinds he has going on, and his orchestration is most unique indeed. He favors these bright, organ-like chords with almost garish harmonic colors, especially the way he scores the brass.
I think personally
Turangalila is a very accessible work of his and a good starting place, though it depends on your individual taste...it is so wide-eyed and heady that while enormously fun, it can become a bit of overload.
Lately I am getting to know his
Des Canyons aux Etoiles (From the Canyons to the Stars), and really am liking it, it is honestly an extremely beautiful work, to me very visual. It's quite far from Turangalila - much more introspective and transparently scored, focused on primarily the piano and only a few instruments at a time.
In the middle of this long work, I found one of the most enjoyable and humorous bits I have had the pleasure to hear from Messiaen yet - the
Appel Interstellaire (Interstellar Call), for solo horn - which could almost stand alone (and surely has at many horn recitals) as it is so engaging and colorfully written. There are many unique effects he gets from the horn - the most fun being a wolf howl - and alternations of flowing lines and urgent blats that I assume would be "starry" language.

In fact, color me crazy, please do, but I get from this piece three distinct characters - the star with attitude (the loud, rambunctious one who begins), the wolf who answers, and the contemplative star, who takes the thoughtful, noble, singing lines.
I haven't gotten to know the
Vingt Regards yet, perhaps soon...I also want to explore the
La Transfiguration more, I thought it amazing the once I've heard it.