Alameda is flat and it boasts many vital business districts. Generally speaking, it's good for walking.
According to an assessment released this week by Walkscore, Alameda's overall walkability measure, based on how easy it is to do errands and get around without an auto, is either 75 (if you look at this list) or 69 (if you search an Island address).
A cool feature: Input your address into Walkscore and get a walkability assessment for your particular neighborhood.
See if you can beat the 2300 block of Buena Vista, which pulls down a near-perfect 98.