if you're using it as your main number, you should. Power Prepaid + UMI30 gives you 2.5gb where the old plan only gives you 1.5gb. Not to mention that the call rates for Power Prepaid are a lot more cheaper(can say the cheapest for short to mid length calls). The only thing that you're losing is the 2x validity so if you're using it as your main number then that is not a concern anymore

If using New Prepaid with UMI, then call rate after using any bundled minutes is same as for Power Prepaid. Also New Prepaid gets 30 mins on-net free calls per day vs 15 mins under Power Prepaid. Main advantage of Power is free data and low call rate without needing to commit to UMI, but the 1x validity means there is pressure to spend RM30/month to avoid credit build-up.

well, if you use it to subscribe for UMI30 every month, then consider it backup but use like main  anyway, if that's the case, I would recommend you U28 instead compared to Power Prepaid + UMI30.

U28 offers 3gb of data, 50 minutes of free calls + 300sms, and yet it is cheaper than Power Prepaid + UMI30(negligible difference to be honest, 29.68 vs Power Prepaid's 30), but it offers more in return, because it is a postpaid plan.

EDIT: double post   

anyway, to add, if you use auto debit, you can get 5% discount and extra 250mb data