Rebirth is a lot better than BR / Caldera IMO.
Caldera as a map is great fun, huge but not many places to hide outside of capital and factory. Verdansk pre Cold war was the best, many of areas to hide, bunkers and some large spaces like Dam.
The introduction of Cold War and Vanguard brought weapons that quickly because almost zero recoil like the Krig, DMR pre nerf (???!!!) and Bren. Many nerfed but gradually the recoil has become so little whilst ADS has increased that if you are spotted first with no cover, all you can do it run/jump around in cirlces.
I really hope the Modern Warfare 2 game brings back Modern Warfare type weapons. Recoil on ARs but faster look down, less recoil on the big LMGs but slow ADS and movement speed.
Lots of people are using the 'Godzilla breath' STG 44 blueprint which is just stupid really. A WW2 assault rifle that shoots blue trace fire rounds with little to no recoil with a high fire rate, high ADS, high damage, 60 round mag and fast movement speed. What are they thinking... Well, I know what they are thinking "We don't care, people buy COD points to buy guns so **** you" If damage was reduced and recoil increased then people wouldnt spend as much.
Bring back days of the Bruen, PKM, Oden, M4A1, Kilo and M13. Basically the guns are quite unbalanced and need sorting out, especially on Caldera where there's not much cover.