Righto, in no particular order then;
Building a basement is the most expensive part of an apartment or commercial building in terms of structure and water-proofing, merely to provide a car park.
A basement in Ireland for habitable use must be carefully detailed to avoid penetration from water under, on and over the ground.
The access requires careful detailing to allow an alternate escape in event of fire - its totally enclosed underground, remember.
The ventilation must be carefully considered because you may have no windows.
The insulation must be carefully considered because a vented cavity is very difficult to include in the design - a constant 10 degrees ground temperature won't achieve carbon neutral status by 2013 by itself.
In areas with a high water table, a basement can cause uplift which must be resisted by specially designed foundations or else counteracted by the weight of the building above.
Where pumped water or effluent disposal is intended you will usually require a separate back up pump.
If you're supposed to be building sustainably, you may require to dispose of the excavation spoils on the site - that's a lot of muck!
If you're a Super-Green Agenda person and considering embodied energy, then this may limit your construction options somewhat.
That having been said [and the above list is off the top of my head, not exhaustive], on a sloping site in Ireland you could in theory find relatively affordable workarounds for a half-basement solution.
In Canada, for example, basements are routinely included in houses because [from one of the recent relocation house programmes - haven't checked this] in Canada you're supposed to build your founds 10ft/3.0M below GL to avoid frost heave.
In America, particularly in Tornado Alley and on the Southwest coast storm cellars may be mandatory - they're certainly popular.
FWIW
ONQ.