Sihing73 pointed out a few key differences between wing chun and bagua, but his characterisation of our forms of attack were a bit off the mark. There are a lot of ways to fight with bagua, and while it often involves moving around behind the opponent, there are countless ways to smash straight through the centre too. I guess you could say that both methods are evasive, though, in that you don’t block attacks so much as deflect them, attack them, or avoid them.
One big difference that nobody has pointed out yet is the difference in footwork. Bagua stepping is perhaps the quickest and most intricate of any martial art (it is well renowned for this) and I found that learning this quickly undermined the more static stances utilised in wing chun. There have been numerous accounts of masters in other styles learning bagua just to glean this aspect of it, whether they be karateka or other Chinese artists.
Bagua does not train muscle groups like wing chun. In bagua most of your power comes from the torque of the waist with force added from all the other counter-coils you instantiate at the joints. I guess that you could say that in bagua one is always coiled, and attacks are often implemented in the trabsitions between opposite extremes of this coil. You’re always loaded for an attack in bagua, and the power comes from the coiling of the entire body rather than from any particular muscle groups. It is wierd for a wing chun practitioner to learn this… the upper, middle and lower body are all linked but working in different directions, so in circle walking your feet move along the circumference of the circle, you hips point at a tangent from it, your waist is tightly twisted inwards and your upper body faces the centre of the circle. All of this structure coils and uncoils to some extent as you actually walk the circle… there is a rambling-dragon metaphor that is sometimes used to explain the apparent indeppendence of the different parts of the body.
As Sihing73 mentioned, there are some locks and throws in bagua, but I think of bagua primarilly as a palm-striking art. Getting out of locks is certainly taught, but putting people into them is a transitory process. Often you will lock up an opponents joints with bagua, but you keep moving through them so that they break. There is no concept of submission fighting. Same goes for throws… some come as a consequence of the way you’ve locked your opponent up, and if you get it right you should break several bones and land the attacker on his head so that his neck breaks. There is a perculiar technique of controlling the attacker’s leg in a throw so that he cannot roll out of it and gets pile-driven instead. There are also some throws that are really secondary to strikes. If, for example, you step into someone’s stance from the side and break their knee from behind (wing chun does this) they will tend to fall backwards over your leg… if you add an upwards strike to the armpit or neck (kinda like diagonal flying in taiji) this will add some momentum. The real point of the attack is the point-strike and the leg break, but a throw is seen as a side effect… you might almost hope the attacker would be dead before he hit the ground. That’s how I practise the lock and throw aspects, anyway - I’m sure there are different emphases in other lineages.
Bagua is a cool art to learn. It is surprisingly vicious but can take a while to pick up. I didn’t want to retain my wing chun once I began, but it is conceivable that anyone could benefit from some circle-walking and the kicking methods it trains. It is a martial art that tends to suit someone who already knows something about fighting (the founder of the system, Dong Haichuan, was said only to teach experienced martial artists) but who is willing to adjust their basic principles.
I would consider xingyi to be a good alternative to wing chun also. I don’t know how compatible it would be to cross-train, but there are some highly destructive, relatively simple fighting methods in there. That’s really just for the interest of anyone else who’s looking to check out an internal art, because I know Straight Blast is committed to his wing chun programme. (Incidentally SB, Damien is very well regarded as an instructor down here in Adelaide… small world!)
Hope you’re not all too bored now 
It’s dangerous to invite a man to plug his passion, Max 
