Going by what I've seen on this site and other Nissan-related sites, the engine is as reliable as any other engine when used as a DD. It does tend to run hot so, if you intend to drive hard, an oil cooler might be indicated.
If you plan on tracking the car, you'll need all the extra cooling you can get and will probably want to upgrade the brakes. You might get better answers in the
Track / Autocross / Drifting / Dragstrip - Nissan 370Z Forum section.
Late edit: Some engines will consume enough oil that they have to be replaced. But these seem to be fairly few and far between and my guess is that more than one of them was due to abuse. Check your level often (but you should be doing that anyway). My engine uses almost no oil at all; never more than a few millimeters on the stick between changes.
