I had similar problems with spikes. I think that it wasn't a problem that those spikes were there. Problem was how you showed them to the player. I died like 4 or 5 times just because I didn't noticed that they are any spikes.
Hum... I wonder how can I make those spikes clearer... I'm thinking I can replace one of the water jumps with spike jump. This would make it evident that there are spikes in that level... What do you guys think?