Well, I have a Bone Necro, with 1 point wonders in the summoning tree...the +skills do the rest of the work..
He's a PvP char, but when I go PvM, I use my army to his full extent..
I can raise 6 skellies and 6 mages and 14 revives, 1 gumby and a merc with insight (7 skellies and mages and 16 revives, but 2 skellies, warrior and mage, and 2 revives will poof when i switch to CTA to Bo), and I don't bother WHAT I revive..I think that's rather pointless...Just revive as you kill stuff..that will provide a constant meat shield army...
As for "reliability", my skellies die a lot less often than the revives... In duels Vs, good characters, when i summon my army, mostly the only thing left of it are gumby and a few skellies...all the revives are wipped out...
However, if you bother getting the right revives (wich can take a while), they can provide a much better temporary defense in PvP then Skellies...
NightFish: I think an exception to that would be glooms/souls...They're extremely overpowered due to a bug...and it's just frightning, in PvM or PvP to see your army fry anything that comes close to you....My favorite Revives...