For the last three days I've been using the Pokeradar to try to find a Shiny Pikachu in Santalune Forest, and let me tell you, it has been the worst.
For one thing, the forest's perspective is a lot different from most areas in the game. It's not as top-down as Pokemon or a 2D Legend of Zelda games are. It's more in line with 3D Zeldas or 3D Mario games.
This means that more often or not, you CANNOT see the patches of grass that are shaking down at the bottom of the area because of how the camera is angled. This makes it very risky to try to get any of the patches of grass below you.
In the red square is a patch where you can see the tip of the grass rustling, but you can't see anything of the patch below.
The blue square is where you can see the whole of one patch and the tip of the one below, but since the top patch will be shaking it would be hard to notice what the other one is doing.
And finally, the yellow square. That spot will forever haunt me. I started up my 20th or so attempt at using the radar and beat two Pikachu. Then. THAT. PATCH. STARTED. SPARKLING. I had done it. A Shiny Pikachu was waiting for me. I headed for that spot, but I hadn't seen that the spot directly to the right of it had also been shaking, veeeeeeeery softly.
"But there doesn't seem to be any Pokemon here."
And that was it... I was left standing in the cold forest... all alone... and it was gone...
EDIT:
Success is mine! After god knows how many tries. I chained ten Pikachu and then the signature noise happened! It happened off-screen and I was pretty sure I wouldn't be able to get it, but I was lucky and landed on the correct tile. It's a quiet nature, which sucks for speed but is good for SP. Attack.
Also, according to Bulbapedia, the poke-radar caps after 40 chain and then you don't have to encounter any more. You just have to re-set the radar until a shiny appears. That would have been helpful information.
EDIT EDIT:I was 20-chain into a Swirlix hunt and I ended up going into a patch that wasn't shaking quite strong enough... and then this guy showed up. I was too surprised to be mad. I really dislike Croagunk so I'm not to thrilled, but I'm sure I can trade it for something.