Since it isn't indicated how its supposed to be interesting, I'll put two different kinds of answers down.
Most interesting design-wise:
3. So many options, yet no matter where you put it off the tee, you have to execute your second shot almost perfectly. You hit your drive or iron to wherever you are most comfortable. It doesn't favor any length of hitter.
Most interesting for the pros in the Masters:
13. How many clutch shots have we seen on this hole through the years? Mid-irons from the hanging lie. Long irons or hybrids from the pine-straw. Pitches hit tight to save par if they go in the tributary of Rae's Creek. Also, the disasters. Tiger putting it off the green, for example. They say it doesn't start until the back nine on Sunday, but I'd go further than that. So long as there aren't water balls on 11 or 12 to shake things up, 13 is where the Masters really starts to get decided.
Least interesting design-wise:
17. That hole is a snoozer without the Eisenhower tree. I'd like to see a bunker be added down the right hand side of the fairway/rough to entice players to play close to it to have the angle into the left side of the green. Also, I think the front bunker should go. I think we'd see balls bounce onto the green from a great recovery from the pine-straw, but also more flubbed chips if players came up short than if the shot was a bunker shot. Because the bunker would be gone, make the small false front run across the entire front of the green rather than just the front left and front right. The green would feel more Mackenzie this way, IMO.
Least interesting for the pros at the Masters:
4. They play from so far back on the back tee that the play is to dump it in the front right bunker rather than have it land on the green and bounce over a lot of the time. There is a reason they move them to the forward tee 2 days of the week. Move the back tee forward to about 210-215 and I think it solves all the issues with the hole at the moment. The other par 3s don't play over 200, so moving it forward would still ask for a longer iron than the others for variety sake.