This polearm is not only good for birds, in just about every non-HNM situation like Einherjar (bar odin)/Limbus/Mamool exp/any farm etc this is better than Hagun, 5-hit + overwhelm merits really make this amazing in the right hands. Of course in harder mobs (Dynamis xarcabard/gods/kirin/sea jailers) Hagun will always reign supreme.
Donwu's right. This polearm is considered one of the top polearms to use. The fight is a bit annoying, in fact it's lag city, but it's totally worth it.
Ryukuro is 100% right in placing this over Gondo for Samurai. the +5 ACC, +5 Attack and +1 base damage of the Tomoe all affect the returns of Penta Thrust. The +6% crit on the Gondo, sadly, does not. If you don't do ZNMs, however, and do RR more than twice in the hopes of getting a Gondo you'll be able to sell off the O. Ingots to buy a Tomoe from a merc LS :)