I did this hike in July 2013, on the evening when I arrived in town. To get to the trail head is very easy: when in downtown, with your back to the shore and facing the hill, simply turn left on the main road and walk about 5 minutes until you cross a bridge (the bridge is over the creek which forms the waterfalls). Most of the hike is on the left side of the creek but you can more or less choose your way, walk through the water, etc, depending on your level of comfort and hiking experience. For the last five minutes you can reach a higher pathway on the right side, or stick close to the water (which is what I did). The 1st waterfall is very nice (I did see better though). Being rainy season the pool was not clear and not very inviting in my opinion.
The decision point is really here - if you want to go to the next waterfalls or not. The climb is on the right side (when facing the waterfall) and the hill is steep, eroded and quite exposed. After a false start I realized that the easiest way is to follow the tree roots. Most of them (but not all; test them!) are very good hand holds. Once you get up you notice that there is a trail (so you could possible access it from a point further downstream?!) which follows the edge of the hill until you get to safe/unexposed ground and there it splits. The right side trail goes deeper in the jungle and might be an interesting hike in itself. The left side trail turns towards the river and crosses first a side stream, after which it climbs steeply to a ridge (again, roots are your friends). From the top of the ridge you go down towards the creek/waterfalls, but not before having to pass the most exposed section of the whole hike - a 10 feet drop with few hand holds and a rope which was very handy (and it held well, at least at that time; again - test it!). That's definitely a place where you don't want to fall - the 10 feet drop can become a 30 feet extremely dangerous drop in a split second).Once you pass this step you get to the banks of the creek, on top of a smaller (2nd) waterfall, with a 3rd waterfall right on top, in quick succession, and a pool in between. Two hikers we met there hesitated and then bailed out on jumping (wisely, in my opinion). Locals told me that some people died while jumping in the waterfalls.
To summarize, accessing the first (and highest) waterfall is a very nice and easy hike, no guide needed. To reach the higher waterfalls by the shortest path is relatively dangerous, but this will obviously depend on your experience more than anything else. It did look like there were other trails, less exposed, which required some detours. Locals said that there was also a much longer trail on the left side, which starts on the road further away from the normal trail head and you won't see the water at all until you reach the upper waterfalls. But that might be a nice jungle walk, and hopefully less exposed.