The ergo's arent bad, but there are MANY different options that you have that are better imo.
I think there mind set was to try and deliver a more ergonomic, compact polymer compared to the Sig pro. It is also possible to change calibers and frame sizes, but it is extremely expensive to do.
Many Sig guru's over at Sigforum find this design to be a complete failure. They are reliable and accurate, but so are many many other guns.