It fits their lore, and it's cool and all, but...
I dunno, I think that a whole guild dedicated to bug bites could find a better way to make it work.
All in all, I think that, for now, Evolve is the only truly good new mechanic. Honestly the RTR guild's got the much better end of the deal. ALL of their mechanics were some level of awesome. Detain? Game breaking, much praised mechanic. Populate? There's a reason 1/1 Birds are now a thing. A tournament topping thing. Scavenge only get's shafted cause GB has better stuff to do than that but it still gets a lot of use. Unleash is effing awesome and and Overload's only flaw is the cards that carry it.
Right now, Battallion, while I do like it, doesn't have the immediate threat effect Detain had and I cant see it getting much tournament play, Extort wastes mana on a bug bite that could be much better used on a better spell, Gruul's just gives a temporary boost worthy of a glorified instant (and it's still one of the better mechanics). Evolve seems good in theory, and is probably the best of the bunch revealed, but "Build your own creature" decks are easy to deactivate with a simple Terminus, or what have you.
Dimir might get a Detain-level of awesome skill, but it still won't make Gatecrash's keywords as cool as RTR's.
Here's hoping the actual cards make up for it, though.
PS: having said that, if I do go to a pre-release event I'm most likely going as Boros.