Clicker training really is a very effective method for many dogs, the clicker makes it so much easier for them to understand what we are trying to communicate to them.
I started training Taj (now 6.5 months old) with a clicker, but I found that I needed to have him respond to my voice as well (often didn't have the clicker and treats on me during non-training times) so I introduced verbal markers (not just verbal cues) as well, especially for training new behaviours and this seemed to ease the frustration he was starting to experience with free shaping new behaviours with the clicker. I think his frustration was based on a) his willingness to please me and his understanding that he wasn't doing what I actually wanted him to do and b) his Border Collie need/compulsion for precision and accuracy!
I still use the clicker, but not quite in the same was as before, and it seems to be working for us, at least for the moment!
Michelle