I doubt there is anyone here who has working knowledge of all the styles. Even within styles there are sub-styles resulting from personal interpretations and understanding of different teachers. I practise a specific sub-style of huang taichi, and i know nothing of chen, yang, wu, sun and hao styles.
I think we should stop worrying about styles and just enjoy taichi.
Zeny has a point, what we can offer are more or less personal our understanding of what differentiates the major styles.
From my perspective:
Chen (the style i practice) is the oldest known historical form of taijiquan originating from the end of Ming / Beginning of Qing era (late 1600's to early 1700's). It is a hybrid style combining known military-based techniques with taoist breathing exercise and philosophy. The forms combine hard and soft, fast and slow movements, emphasizing 'silk reeling', which is a spiraling kind of energy infused into every movement. Chen forms are quite distinct, you can instantly recognize it by the use of stomping, jumping, fast punches and kicks in between slow and deliberate moves.
Yang style is the most widespread and popular style at the moment, and is probably what people have in mind when one mentions taijiquan. Yang style is directly descended from Chen, but there is a lot of speculation as to why the 2 styles seem to differ so much. Yang style is slow and meticulous, and does not include (as far as I can tell) fast or hard moves in forms. While some have suggested that the Yang style either discarded the hard / fast moves in order to cater to aristocratic students, or that Yang Lu Chan learned a different form of Taijiquan than what we know of as Chen Style today, my own view is that Yang style chose to concentrate on the more subtle elements and evolved as it was no longer kept within the confines of Chen Village. In fact, Yang Style is very fragmented in my view, with very different interpretations and offshoots. Zeny's Huang Style is what I would consider one of the modern offshoots of Yang.
Wu (å“) style is descended from Yang, but is recognizably different in that it is a 'small frame' style. Movements are smaller and more attention is paid to the internal mechanics.
Wu (ę¦) or Wu-Hao in English, so as not to confuse with Wu (å“) is a relatively rare style that to me seems quite similar to Wu (å“) in that they are both small frame forms. This style is also descended from Yang, but the creator also studied in Chen Village and combined elements of Chen small frame into his style.
Sun style is the most modern of the bunch. It is descended from Wu-Hao, but takes in elements of other so called 'internal' arts such as xingyi and bagua, so if you are familiar with the characteristics of these styles, you would be able to recognize them in Sun forms.
There is another major (arguably) style known as 'Zhaobao', after the village it originated from. The origins of this style is quite controversial, as it is claimed by some practitioners that it pre-dates Chen style, while others, especially Chen stylists, who say that it descended from Small frame Chen. I am least familiar with this style so I don't think I can comment on the characteristics.