At a cost of 4 HQ Interface doubles the effectiveness of your accesses when running on HQ runs. Those four will have paid for themselves easily once the runner is able to access agendas! This will also cause the corp to focus more on protecting HQ hence slowing down his/her tempo.
Comparison with Legwork
HQ Interface is much more flexible, can be used over & over for the rest of the game (earlier the better)
Can be used in powerful combination with Legwork & Nerve Agent
Can combo well with itself if you have multiple copies installed
HQ Interface is more expensive than Legwork and would need to be used 2-3 times before it catches up economically
Doesn't dig nearly as deep into HQ as Legwork
The corp will likely have more time to build up HQ defenses
Comparison/Combo with Nerve Agent
Is hardware making it less of a target VS Nerve Agent
Since it's not a virus, there are no virus tokens to be purged, meaning it's ready all the time
Since it's hardware vs program, no MU cost penalty
Costs one more , but not too bad, since At only one more credit than Nerve Agent,
Only +1 card access per installation of HQ Interface vs the possibility of other affects that can quickly pump up virus tokens on Nerve Agent to give it near infinite card draw
All things in balance, if you are going for HQ card access, this card is worth a look, particularly for Criminals, at two influence cost, maybe in certain cases Shaper & Anarch too.
--It just saddens me when I see cards with no reviews. If you appreciated this review, please give a heart and I'll be encouraged to write more.