In my experience, ExtraBiomes is something just like GregTech: it needs to be configured to suit one's personal style.
I really like how the mod gives you config options to, for example, enable or disable village generation in every single biome, even vanilla ones. And you can toggle on and off each addon biome as well. I love the red stone and the cracked sand and the pale acacia wood as building material. "Cosmetic" is a perfectly viable purpose for an item in a game where the whole point is building something cool.
What I don't like is how similar many added biomes are. For example, there is not one biome where Redwood trees grow; there's at least four, maybe five of them. One type has snow, another doesn't. One type is rich green, the other pale green. One type has lots of grass and undergrowth, another doesn't. These are fine points that are completely lost to the player who is faced with an entire map full of redwood trees, kilometers in each direction, the ground too mountainous to build anything, FPS on older computers slowed to a crawl by the sheer amount of geometry and the task of cutting even a single tree down taking an entire ingame day, if not more. This is also true to a lesser extent for other biome types, but its the redwood trees that really slap it into your face. This by the way is the reason why people feel that there's hardly any vanilla biomes left - because the mods spams an unnecessary number of almost identical extra biomes.
Now, the issues with wood being incompatible with recipes and such might potentially be fixed already, thanks to Forge's resource dictionary expanding to materials beyond just ores. The issues with the biome spam, that's up to the user to correct in the config file, by disabling all of the essentially duplicate biomes so that only a few key ones that truly stand out are left.