Shimano 5700 series 105 shifters are absolute crap. Poorly designed cable routing means the shifting is finicky and they're prone to having shifter cable heads break off in the shifter.
I hated mine for the 3 years I had them.
The current 10-speed Tiagra won't work with the older generation Shimano 10-speed stuff because they changed the cable pull--I think so the RD would be cross-compatible with 11sp shifters.