It had some ridiculously large shoes to fill.

Like for what it is, it sure has some warts, but it's actually pretty decent, or at least not AS bad as most probably remember it being.

I blame the consolitis, which butchered everything down into tiny mostly-independent loading zones.

The same engine and problems also applied to Thief 3, although it was less of an issue because your average speed of sneaking through the zones was slower. :p