I like the way GW2 is doing microtransactions. There are many ways to continue getting better gear and exp in the game, such as PvE, PvP, gathering and crafting, and exploration. Microtransactions don't really modify or enhance any of these. Instead, they add mostly cosmetic features, such as sunglasses or a new hat (stat-free) or a mini-pet that does not join in combat. There are a few enhancements, such as a 1% exp or karma increase for a set period of time, but they are small upgrades that wear off and don't drastically change the experience or give an edge.

It may change in the future, but for now it's great.