According to the Battle Reports, the Terrans seem to be a bit boring with the Marine+Marauder combo..
Which turns to be an all-out lethal combination. Effective against most air units, deadly against ground..

Maybe it was because the same guys were playing, but it seemed to me that massing the new M&M combination and creating 2 Banshees worked against Protoss and Zerg either.
Maybe more Hellions instead of Marines against Protoss, but still quite boring.

Where were the Tanks? There were no Tanks in a TvP game O_o
I guess the reason for this is that the Marauders are now simply imba. (basically too much HP, armor, etc.)

Opinions on that matter?

Already mentioned by a few, but M&Ms are very susceptible to any AoE type abilities/attacks. For example, they fall quickly to Banelings (if they get close enough, usually using burrow), Psi Storm, Colossi, Siege Tanks, and Disease (does 100 damage to units in an area but will not kill the unit - replacing fungal infestation).

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Q u o t e:
Karune, is the Infestor's "Spawn 5 Infested Terrans" ability being reconsidered?

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Everything is still possible and I believe there will be mild to extreme balance changes from now to beta and throughout beta as well. Keeping an open mind is very important in balancing this game, which is exactly what the StarCraft II team is doing.