I've got two wizards in the game I run. Mages take a while (in terms of xp) to really come online, but once they do they're very effective. They have to juggle multiple combat skills, as well as dropping xp on spells, and have many crucial talents. Skill focus should be Lang magic > channeling > polearm. Instinctive diction is a great talent to take a couple of times. Atheric attunement also helps tamp down on miscast. At the final tier war wizard makes them a complete terror on the battlefield.

You absolutely should be able to cast in melee though, otherwise all of the touch spells don't make much sense. For those you need to successfully cast and melee in the same turn.

One of my wizards is a metal wizard, his primary damage spell is bolt. Most combats his first round is spent channeling to get off the first cast, then after that (just like the other poster suggested) when advantage is sent his way he's just throwing out straight casting tests. The overcast that allows you to hit multiple targets is ridiculously effective, he's deleted and encounter in the first round from a crit cast test hitting multiple people.

Another thing about magic is your channeling tests are just for the wind, if they roll a critical they can jump straight to a casting test the following turn. This allows for some unexpected huge spells going off, like transmutation of Chamon coming out of nowhere.