World of Tanks really is a strange beast. It's both exciting and infuriating in equal measure, sometimes at the same time. I've been playing in short bursts and alternating between a Tier 3 light tank (the M3 Stuart) and a Tier 3 medium tank (the M2 Medium Tank). I've escaped my run of bad luck getting nothing but high tier opponents, and have gotten more matches with mixed groups. I've even gotten a few where my tank was one of the biggest things on the maps.
It was on one of those rare battles that I got the Top Gun acheivement last night. This requires getting 6 kills in a single battle. Keep in mind that there are a maximum of 15 enemies in a battle, everyone only gets one life, and you have 14 allies also trying to take out the enemy. Getting the Top Gun award means taking out nearly half the opposing team by yourself. I'd like to say it was superior skill that got me there, but really it was luck and the fact that I had the toughest vehicle on the map with the biggest gun.
Which, sadly, demonstrates one of the things that is both frustrating and exciting in World of Tanks -- the luck of the draw. If you're in a tier 3 and get put in a battle with mostly tier 2s and just a few opposing tier 3s (like I did last night) you know you're probably in for a fun match. You're far from invulnerable, but you're dangerous. The very next match though, might pit you mostly against tier 5s, and suddenly you're almost useless. If you're in a fast light tank you can still play a role as a spotter (which I did in one fun battle last night) but the M2 Medium tank isn't a very good scout, it's too slow and too easy to see.
Speaking of spotting, World of Tanks has a pretty complex sight/sensor/stealth mechanic. Every tank has a nominal range at which they can spot the enemy (sight range). They also have a radio range with which they can report the position of spotted enemies to allies (who can then also see them). Many tanks also have a modifier to how easily spotted they are (stealth), with Tank Destroyers being the stealthiest and Heavy Tanks being the easiest to spot. Moving makes you easier to spot, as does opening fire, whereas sitting still and not shooting while hiding behind some bushes can make you hard to spot. A Tank Destroyer with a camo net, skilled crew, and good cover can be nearly undetectable until they move or open fire. This results in the rather jarring situation of tanks suddenly popping into view a short distance away when the game determines you can see them after all. It also means it's not unusual be taking fire without being able to see the enemy at all. All in all it's realistic enough, and adds some tension to navigating the map. Unlike a typical MMO PvP match you can't see the enemy from the other side of the map unless someone has spotted them for you. It also resulted in two tier 4 tanks rolling up behind me while I was in a sniping position and blowing me to bits before I'd even realized they were there. Good for them though, they ran a gauntlet of allied spotters without ever being detected.
I like this game, though I really wish there was more to it. The wikipedia entry talks about clan battles and a campaign map, but I don't see any of that when I start up the client. Not sure if the wiki is wrong, or the U.S. has gotten a different version than Europe.