I'm probably still considered a new player, I have a few thousand battles now.  My name on WoT is Bribarian if you're interested in stats etc.  Not that they are anything to rave about.  If you're thinking about playing it I'd say it's worth checking out, I came across it through twitch.tv.

The game is basically an FPS in a tank.  You can play one tank if you'd like, making it elite, putting all the best equipment on it, advancing a crew.  Or you can level up to the next tier.  There are ten tiers in the game.   Lots of consumables and addons for tanks availables Example: Camouflage net for better hiding.

The battles are done by your tier.  For instance, if you are in a Tier IV tank, you will find yourself in battles with Tier III, IV, V, VI, and sometimes VII.  This is just an estimate on it and it varies by tanks.  Artillery and scout tanks will end up in higher tiers than their own usually.  The battle consist of capture points and an attack/defend style.  2 teams 15 players.

The Good:

It's free

Battles are fast, you login, hit battle, and you're in a game.  Making it accessible to people with time constraints.

The Devs seems pretty receptive to player feedback, they've removed hated maps as well as adjusted the Tier placement. 

Community is better than average, Only thing I've noticed about this community is it has a "blame the other guy" attitude in games.  "If I die it was your fault" which gets old, then you have spammers, the typical internet dbags are going to be found here just like everywhere else on the net.

Graphics are good enough, even well done for a free game.  Maps are done good as well, designed nicely for a tank FPS, good variety too.  The look of the tanks also turned me on to the game. 

Huge variety of WW2 - Post WW2 tanks to level up, to equip.  The crew skills make sense and arent overpowering.   Five different classes,  Heavy, Medium, Light, Tank Destroyer, and the hated artillery.

Considering the overall amount of different guns and tanks, I'd have to say the game is pretty well balanced, although it's really about finding that right tank in the right Tier.   You will come across a tank you just get ruined in, but you will also find a tank you can do well in, it varies from person to person.

Teamwork is a must and the game rewards you for it with wins.  Wins also reward everyone more credits which makes sense.  Basically the better you do the faster you will get credits and experience on your tanks.  Which is how it should be rather than the "everyone gets a trophy" type we see in other games today.

Also available are clans, clan battles, I dont have a lot of experience with these yet. 

The Bad:

Some Pay-to-Win aspects.  Gold rounds which give players an in-game advantage.  There are Premium tanks which you can buy right out of their shop, but I dont believe they are any more powerful than the tanks available to everyone.  You can also purchase a premium membership which is a faster route to Experience and Credits.  This isnt really a bad thing as the company does have to make money however I wish they would have left gold round out.

Grinding - There is some grinding involved, especially at the higher level tiers.  No avoiding it really unless you're a godly player with a premium account.

Lag Spikes.  Overall the game performs well online, however I have noticed from time to time lag spikes which will pause the game for 1-3 seconds.  Makes it crappy if I'm in a scout/fast tank.

At times the game can be frustrating.  For instance, you may log in and lose 10 battles in a row due to a poor team or just bad luck.  Luck is always a factor in FPS type games, no getting around it.

Artillery is also very much a hated aspect of the game.  I've found in my personal experience that Tier 5 artillery and below arent that bad, but Tier 6 and higher have potential to one shot tanks.  Higher tier artillery seems too powerful considering it's role, but I havent felt it's ruined the game, although getting one shotted will amaze me. 

Some players have complaints with how detection works, I personally felt it's pretty decent, there are times when "invisible tanks" will be shooting at you because of how detection is done in this game.

Anyways, I hope you found this helpful, only really way to know if it's for you is to go download it and fire it up.

For an expert player like me (more than 1 year of experience, playing everyday, with a premium tier 8 tank (T34, I got it for free :D )) this is how the game looks to me

Pros

- If someday you barely have time to play, you can play one or two battles and have fun

- It's free once you get a premium tier 8 tank to make money

- Enjoyable, half reallistic, and this is the only game that recently got me hooked up for a year (more than any other game from the last years could)

- The clan wars are awesome, but the difficult to get a territory is very high, there are very good teams out there), Tank Companies are also interesting, but in the end they won't reward you with gold, just fun. This is like the previous step towards Clan Wars

- Experience and playing in a clan with other players is very useful to learn about the game. Even after thousands of battles I still learn something from my mates, and they from me. Also it's even more fun if you can talk to other people through VoIP

- Gold ammo is not an issue for me. In random battles nobody wastes their own money for winning. And in Clan Wars.... well, it helps, but those rounds won't win the battles without good tactics.

Cons

- You need a premium account, or be invited by a premium player to play Tank Companies, Clan Wars, or enjoy a Platoon of 3 players (it's free if you play with just one friend)

- You have to pay to create a clan, but joining one is free

- Random Battles are shooting ranges for high tier tanks, however you can enjoy playing with a medium tier tank if you know its limits (and if you are lucky with the match making system)

- At certain point, you need a tank to make money (luckly only a tier 8 premium tank is enough to allow you to progress easily, though you need to know how to drive it)

- A lot of players complain about the arties, but they aren't the almighty god punishing you, they have their limits.

I am a gold buyer and let me tell you, it does not give you an advantage in any match. It might make the grind less of a pain (it doesnt). WoT is a game for people who:

Love tanks! <-----me!

Have no time<-------me!