The data depends on the model, some don't have battery life estimates (that I've found at least). Not that estimates are reality, but it's still nice to have it all. Everything that's in the database is shown. Also, Amazon doesn't sell all models so the reviews don't always get tied in. I'm looking to expand out to reviews on Shopping.com as well since they cover more models. If you're comparing a model that does have Amazon reviews and one that doesn't, the one that doesn't will show up as a ?. The AWS interface can be a bit different for items that are sold through a third-party, so that might be affecting some models as well, I'll have to check on it.