Combat in Wizard101 is based on trading cards. You put together a deck, of which you draw a random hand of 7 at the start of combat, and redraw new cards for every card you played. Cards have a cost from 0 to 4 "pips", and you gain one pip every round. So if you want to play higher cost cards, you need to either pass or play only 0 cost cards for some rounds to accumulate pips. Every card you play results in some animation, usually summoning something that attacks the enemy. The downside of that is that you can't turn off or speed up those animations, so every combat lasts even longer than in WAR.
Cards come in 7 different magic schools, fire, ice, myth, storms, life, death, and balance. You choose one of these schools at the start, but you also get "training points" during your career, which allow you to buy spells from other schools. But as you can only buy the higher level spells of other schools if you already have all the lower level spells of that same school, it is usually best to put all training points into the same secondary school. You have infinite copies of the spells you learned. In addition to that you can put golden "treasure" spell cards into your sideboard, which you can access by discarding cards in combat and pressing the draw button. These treasure cards are one use only, and you can get them as loot, or quest reward, or buy them for gold.
Besides cards you also collect gear, which has bonuses to your health and mana, or to the spell damage of some school, or to spell resistances. Some items even give you access to new spells. Health and mana does not regenerate after combat. You need to find red and blue wisps to recharge them, or teleport back to the city where you can play various puzzle games at the fairgrounds to replenish.
Gameplay is typical for an easy MMO: You get quests telling you to kill some monsters or to talk to somebody. Doing the quests and killing monsters gives you xp, which make your level go up, which gives you more health and mana, as well as access to more spells. The zones in Wizard City are streets, where (how educational) you are safe if you stick to the sidewalk, but can be attacked on the road. If you run into a monster, a magical circle opens up with you and that monster, where you exchange attacks until one of you dies. Other players can join that circle, but then other monsters can add to the combat too, so that up to 4 players can fight up to 4 monsters at the same time. Big advantage: If you fight in a group all the kills count for everyone, so if you have to kill X mobs it is often faster to join other player's fights than soloing everything. But you can't form fixed groups, and there aren't any guilds in the game either. You do have a friends list, and you can teleport to where your friends are. The quest line is rather linear, if you play Wizards101 a second time, you'll play exactly the same quests again, only with presumably different spells.
Wizard101 is in the last phase of the beta, the headstart phase in which characters won't be deleted any more for release. Once the game is released, you can still try it for free. Half of the first world, Wizard City, is accessible without paying, which means you can level up to about level 12 and decide whether you like the game. If you want to go on, there is a monthly subscription fee of $9.95. At some point in the future KingsIsle also wants to introduce a RMT system, where you can pay real dollars for a second virtual currency called crowns. Crowns can be exchanged against gold, or you can buy extra good gear with crowns, if you want to advance faster.
Wizard101 is a good game. It is remarkably stable and bug-free. It isn't as big as WoW or WAR, and more linear. But if you can overlook the child-suitable graphics and like more tactical combat than classic MMORPGs can offer, Wizard101 might be the game for you. And as you can try it for free, I can only suggest checking it out. Recommended!