It's not really a fair comparison. Atom was an attempt to hug the low-end of the computing market with a low-power CPU for use in netbooks. ARM on the other hand is a smartphone/tablet system-on-a-chip which is in a completely separate performance/power-usage realm. Different design goals, different tradeoffs.
However, Intel found out that the power/performance tradeoffs for the original Atom were not what the market wanted and they've continued to evolve the design. Today there is the "Medfield" Atom system-on-a-chip which is already making its way into smartphones and already giving ARM a run for its money. Given Intel's history and their initial level of success with this first generation SoC design it's definitely far too soon to write off Atom and bask in ARM triumphalism.
However, Intel found out that the power/performance tradeoffs for the original Atom were not what the market wanted and they've continued to evolve the design. Today there is the "Medfield" Atom system-on-a-chip which is already making its way into smartphones and already giving ARM a run for its money. Given Intel's history and their initial level of success with this first generation SoC design it's definitely far too soon to write off Atom and bask in ARM triumphalism.