True, it was more well balanced in the first AVP regarding energy and health. I thought there was an increase in challenge when you escape the pods though (oh fond memories) and crash in the moutains full of xenos. The sheer number of attackers kept me on my toes, not for very long I must admit, but still I remember that as a more challenging moment.
It could have been better if they threw more Predaliens and Praetorians at you. IIRC you encounter less of those than with the marine.