Ikkaku is a tall and lean-built man sporting a bald head, and is in fact made fun of by a lot of people, especially 11th Division Lieutenant Yachiru Kusajishi, who calls him either "cue ball", "chrome dome", or "pachinko-head" (as a result of her fondness for giving people nicknames or when he questions her direction skills). Ikkaku's bald scalp is very reflective when seen under the sun, causing the members of the 8th and 11th Divisions to mistake it for a full moon in one of the omake segments, much to his chagrin. He also has distinctive small red markings at the outer corner of his eyes. Ikkaku has a scar running down the left side of his chest that he gained while fighting Ichigo Kurosaki during the Soul Society Arc. He wears the standard Shinigami robes with the exception of no tabi with his sandals. Seventeen months after Aizen's defeat, Ikkaku sports a gold-plated shoulder armor on his right arm printed with the kanji for "dragon" (龍) on it.
In terms of his attitude, Ikkaku is a stereotypical 11th Division member — violent, fight-loving, and rude. This has been noted by Tetsuzaemon Iba, among others. He loves fighting so much that he is unwilling to travel anywhere without a sword, resorting to carrying a wooden one when posing as a student at Ichigo Kurosaki's school. Ikkaku is very self-conscious about his baldness to the point, often insisting that he's not bald and his head is "shaven" while it is obvious that it isn't. He will threaten anyone that points this out.
Ikkaku shares many personality traits with his division's captain, Kenpachi Zaraki, which explains why they have such respect for each another. Like Kenpachi, Ikkaku considers fighting fun, and tries to get as much fun as he can, even willing to take deadly risks to drag out the fight for as long as possible. He also shares Kenpachi's penchant for limiting his skills in order for fights to last longer (in his case, using his Bankai, or even his Shikai, as a last resort against his opponents). Ikkaku is even seen constantly smiling like Kenpachi when engaging in a fight with a formidable opponent.
Like all 11th Division members, he considers the only honorable battles to be those that are fought one-on-one. Even the threat of death is not a reason to ignore this fact, as they believe that the winner is only to be determined when the other dies. In his fight with Arrancar Choe Neng Poww, Ikkaku was losing poorly, yet refused to surrender.
However, Ikkaku does have a sense of loyalty and responsibility, unlike many of the lower-ranked 11th Division members and is fiercely loyal to his captain, under whose command he wishes to die. He does consider surviving an otherwise lost battle good luck, as his captain taught him, and is also sensible enough to carry a blood-clotting ointment in the hilt of his Zanpakutō.
Shikai Special Ability:
Ikkaku uses the command "Split" (裂けろ, sakero; "Split apart" in the English dub) to separate his naginata into its true form which is a Sansetsukon (Three Sectional Staff), after which the sections can independently reconnect and separate again at will. This special ability surprises one's opponents when they first attack. These chains are also able to extend a fair length, allowing Ikkaku to swing his weapon like a flail for mid-range attacks.
Bankai Special Ability:
Ikkaku's Bankai, like his Shikai, is quite unusual. Aside from the increase in power, his Bankai offers no special abilities and no special defense properties. It releases some reiatsu which starts to grow in strength. Ikkaku treats Hōzukimaru a lot different than others (as they just let theirs slumber and use it when they want to do Bankai). But if he forces it to awaken suddenly, cutting the enemy and not getting cut becomes a lot harder to handle than it should be. Thus Ikkaku's Bankai gets increasingly more powerful as the fight drags on. After he performs his Bankai, the dragon crest will slowly fill in with crimson dye as Ikkaku's Spiritual Pressure rises. It fills faster when he spins Hōzukimaru with the center handle. Ikkaku comments that his Zanpakutō is actually very lazy in battle (in stark contrast to Ikkaku himself) and needs to be woken up through causing or receiving injury; which would explain its ability to accumulate attacking power the longer the fight extends. When the crest is completely filled, Hōzukimaru is at its full power. However, the force of unleashing so much power can leave his Zanpakutō's edge brittle under excessive stress.
Info from : http://bleach.wikia.com/
Label: Gotei 13 Eleventh Division