It's been released on the PS2, so I would assume we'll see it on our PC's sometime soon. I didn't buy Breakthrough, but I played Spearhead, which on the Hardest difficulty setting didn't take me as long, or seemed as hard as the Original on Normal. I should go back and play MOH:AA on Hard and compare.
I'm a little spoiled with the BF1942 mods/game just for the interactivity of it, but MOH has a special place on my HDD anyway. I think it has to do with the realism ( pure ) and the soundtrack, sounds, evironments really "bring you there". The Normandy invasion recreation was so intense, I actually felt apathy for the soldiers that where actually there. I don't know if I could have survived that in one piece if I were them.
Pacific Assault sounds to be more of the same, and that's what I'd expect from a great series like this. Expansion packs are just that though, expansions. They never re-live the original experience in quite the same way. They are short, and sometimes hastily produced, although I don't know if I could put that stereotype on the one I played ( spearhead ).
MOH, IMO, is an excellent single player experience, and the online experience is excellent also. If Pacific Assault is of this same caliber, then I'll be back to post that it was money well spent.