MW3's rehashing was scandalous, that much is certain, but I don't think it's very fair to gauge Infinity Ward (whether the old or the new one) based on that game. Due to the massive IW exodus and to Activision's obvious demands to put out a COD game any way possible by the holiday season, neither the people left at IW nor SledgeHammer had many options other than reusing lots of elements from MW2.
Ghosts, on the other hand, is a better indication of how much (the new) IW can switch things around. It has more new perk additions than any other recent COD, it has many new unique weapons even including a whole new weapon category, new modes, Extinction, and since the UI was mentioned, I'd argue that Ghosts' has been the one to change the most. Even MW3 brought things such as strike packages and Kill Confirmed (arguably the best alternative to TDM ever put in a COD game) to the table. IW gets called out a lot for their recycling, but it's important to note that Treyarch too recycles lots and lots of elements, such as weapon models and reload animations (although in all fairness, every COD developer will probably always do this).
As far as the old IW goes, COD4 and MW2 will never be touched by Treyarch in terms of innovation within the series. Even Blacks Ops 1 was essentially just a rebalance of all of the elements introduced in MW2. People bitched about Commando, Danger Close, OMA, the ridiculous killstreaks and so on, so Treyarch cut some of those out, rebalanced what was left, and gave it a Cold War flavor. I wouldn't call that particularly innovative.
Again, I understand perfectly well when someone prefers Treyarch's games. I just really don't get why one developer gets such insane amounts of bashing and trashing, while the otther is exempt from that. As someone who prefers IW's games, it's frustrating to come into every COD thread and find the same picture every single time.
