Do you think groundwater seepage would be a nuisance or a benefit?

I don't think there will be many areas on Mars where it's likely you would have groundwater seepage. The dry valleys in the Antarctic are closest Analogs to Earth- your typical deserts on Earth are almost swamps in comparison to Mars. On Earth and in a deserts you can dig a well and get water in some places; on Mars there probably less sites where you could find groundwater [and unless it's in a volcanic area or more than few miles below the surface it's going to be frozen solid].

In other words are very unlikely to get groundwater unless you were looking for it and on the dry maritian planet, it would definitely be a benefit.

But perhaps you are thinking of tunnelling miles under the surface. If you were to build deep subterranian colonies, it seems that you would tunnel towards some desirable location (such as a place suspected of having large amount of water). I can envision the possiblity that a tunneling machine could be main piece equipment used to begin a Martian colony.