The only other Ultra Magnus in my collection is the Animated version. So the closest comparison I can make is with TR Powermaster OP who I understand is somewhat based on CW Ultra Magnus.

My thoughts on the Siege version are that 3 out of 4 of the modes are OK to very good (battle robot mode is best and basic truck mode is OK). The problem with my version is the trailer truck mode. Only about four to six wheels actually touch the ground with the front and back two being the ones that make definitive contact.