Other: I don't have a clue what a "micro transaction" actually is. By itself, I would have gone for Shadowsoldier's definition...
...in other words: micro transaction=mere cosmetic changes. But going by other replies, it's like it is supposed to be "everything that you pay in addition to the game itself".
So without a clear knowledge of what I'm actually supposed to be liking or not liking, I can only answer "mu".
Mu is something like "the question is wrong". In other words: I honestly can't answer it without a clear definition of what is and what isn't a micro-transaction*.
Going by the 'mere cosmetic changes' definition, I'm going with "I couldn't care less".
*according to an online dictionary, it is supposed to be "anything that has to be paid a small fee to access". While that does clear SOME things up, it's easy to play devil's advocate and call red alert 3: uprising a micro transaction, as I bought it in a humble bundle.
Granted it is not as bad as MMO or casual gaming but yeah the definition can be a bit fluid.
The method has technically been around for years, longer if you consider most fruit/slot machines are almost exactly this (you might get money out of a fruit machine). It rose to prominence in recent years as many facebook, flash, mobile phone and web based games used the model, I even saw it on a 3ds game the other day in Bravely Default and there were a few "full" games that use it. Free to play games (be they simple flash things or full 3d) make extensive use of this sort of thing.
Generally it was noted that being paid for your games was nice for developers and adverts do not cut it in a lot of things. How they implement it varies quite a bit.
Some games use purely cosmetic things.
Some games use it to allow variation in play styles. Going back to an earlier example if say damage per second was a thing then if you halfed the damage but doubled the fire rate you have basically the same gun but it might allow for a slightly different play style.
Some games use it to allow you to select another character. You have 10 character types to choose from but if you are going random play then you can have a user pay to play as another character type.
Some games use it to buy collectible cards of a sort.
Some games use it to allow players to boost stats either temporarily or though it is more of a thing in the next one you can also get permanent boosts. On the cards thing you can also pay to improve your luck.
Some games use it to allow access to exclusive maps, areas, abilities (as in not just similar weapons but slightly different but whole other classes of abilities-- only paid users* can use magic and such).
*only paid or those that put in several hundred hours so practically speaking only those that paid still counts but has been seen.
Some games use it to get a player to quickly progress through a game. This can serve multiple purposes -- just because it takes 2 hours to play does not mean it took 2 hours to build and all that but if someone has paid you then it becomes less of an issue.
Some times this makes no broad difference to gameplay other than free to play people do not have as many strategies available to them (I have only the starting 5 guns or something where paid have 10 more, as no gun should be overpowered and the game should still be skill based this is not such a problem). Other times developers can crank the difficulty right up so only people that pay can get anywhere in the game. The latter is usually termed pay to win and is often seen in the Korean MMO side of things, it is also what several people assume all such games are (and such cynicism is not unwarranted a lot of the time). All seem to appeal to the sunk cost fallacy either on the time (why you may want to get people to sign in every day and delay them from going forward) or the money front.
In all cases I have ever seen this allows people to spend far far more money than a normal game might cost.
I have not truly investigated this like I have some other things and I have seen some things do it well (Illyriad, despite having an interesting fanbase, probably being one of the better examples). It gets a bit more complex as many games will hold contests for things that might cost money, might technically allow you to play fully and for free if you sign in every day (you might be able to miss a few each month but not many), abstract away costs with "points/tokens/coins" and other tricks more commonly seen with con artists and others that abuse the lessons psychology teaches us (sign your friends up and the like).