Colombia isn't at all dangerous, so no need to worry about that at all. The people are great and very happy to see tourists. I would recommend this trip.
I spent more money than I expected, primarily because I drank wine, which is not really drunk out there and is expensive. You are better sticking to beer if you are economising (or water!).
Not all the hotels had hot water (I'd been told they had) which is why I haven't put the holiday down as five stars. We had hot water only half the time, which didn't matter to everyone, as it wasn't cold, but I am keen on hot water.
I did the riding in the coffee region along with a fellow travelling companion (instead of the walk). We had told them we were inexperienced riders. The riding is unsuitable for inexperienced riders. No helmets provided, but also on very rocky terrain, across rivers and up steep climbs. My companion got thrown off twice (amazingly she got back on after the first time). It was very dangerous and I would only recommend this ride to very experienced riders with riding hats.
On the walking day in the coffee region we set off at 11 and didn't get back until around 5, so I would recommend eating something before setting off. Otherwise you will be very hungry.
Take insect repellant - quite a lot of bitey things around.
In Tayrona national park, five of us rented a cabin to share there and then (we decided we couldn't face the hammocks).. It was fabulous and excellent value between the five of us. And it had hot water!
Not too many early starts, which was great.