There aren't really any places that walkers can get to that current vehicles can't. While you might say that they can get into hilly terrain better, can they do it and move about well? If you were a commander that had to assault a mountain outpost, would you rather do it with a mech or with good air support? They will be overly ponderous in the terrain they have been touted as excelling in, or sitting ducks for guerillas with heavy weapons.
Also, the complexity of the mechs will make them prohibitively expensive to operate. To pack as much into these vehicles as most mechs display, there would have to be a good amount of miniturization on some big mechanical equipment...not to mention the power plant. Motors and actuators to operate the limbs, beam weapons, missiles...how many missiles can you fit into a walking tank?
What about safety considerations for the pilot? The M1 Abrams has a compartmented turret so that if the ammunition for the main gun starts to cook off the occupants of the turret will not be killed or severely injured. Will the pilot tub for a mech offer the same level of protection?
This leads me to ask, what level of metallurgy does the manufacturer possess? A running mech is going to create enormous stress on all joints. Failure *WILL* happen. Can they take weapon recoil? What about the excess weight of the armor? What about stresses from reactive armor detonations? You know someone will mount it...
What about sensors? Target and fire control radar and computers take up space.
Pilot controls? To be responsive, the control computer will have to be exceedingly powerful by current standards.
As a full on BattleMech (from anime or wherever) no way...as an oversized suit of battledress, sure, why not?
Now, that's not to say some government on a balkanized world won't make a stupid decision and build a bunch. There neighbors likely won't since conventional combat vehicles will be much cheaper and as or more effective than mechs.
Just my opinion. Take it or leave it.