The Java SDKs are bigger, and what's IMO worse: in Lambda the Python and JavaScript SDKs are automatically installed but the Java SDK is not automagically available on the classpath. Since Lambda is an environment where both artifact size and startup latency matters a lot, this kind of hobbles Java Lambdas.

(I work around this mostly by using native-image.)

As I found out in this bug, v3, despite being released last year, is unusable.

You can't even stream an object to S3. https://github.com/aws/aws-sdk-js-v3/issues/2348

I was pretty shocked by the bad quality of the Cognito JS library (which is now superseded by the Amplify JS library, afaik). The API design itself was really bad and error handling was based on parsing the textual messages of the HTTP responses (or at least something along those lines). In general I really do like AWS but it made me reluctant to suggest Congito to any of our clients (as opposed to say Firebase Auth which has a nice API and just works).

> I was pretty shocked by the bad quality of the Cognito JS library (which is now superseded by the Amplify JS library, afaik).

Subsumed within rather than superceded, AFAICT—in fact, I’ve had to use notionally outdated documentation (actually, I think it was actually Stack Overflow answers, but...) for the former to fill gaps in that for the latter, so I’m relatively certain of the relationship.

AWS SDK APIs tend to mix poor design with poor documentation, often being extremely leaky abstractions on top of the HTTP APIs, which themselves aren’t masterpieces of either design or documentation.

The PHP SDK is so bad, https://github.com/async-aws/ exists and one of the stated goals is "One should be able to read the code and follow the logic". https://bref.sh/ which allows using PHP to write AWS Lambda functions easily uses async-aws, for example.

This problem is what lead me to building out my own s3-compatible implementation, sure it doesn't have all the bells and whistles that the official library has but it does what I need and is under 10kb in size.