I'm in the middle. I've been using Python since the early 2.x series.

The good parts are that the inbuilt data structures and their apis are efficient and clean enough to write code that's mostly readable. Most of the heavy lifting is done in hand tuned C and performance intensive external modules are also written in C. There are several good projects that are written using it and while it's not theoretically perfect, it's useful enough. Like Stroustrup said - there are 2 kinds of the languages, ones that everyone complains about and ones that no one uses.

The bad parts are that it's very easy to use. Almost in a Visual Basic "producing crap just takes a squeeze" kind of way. It opened up programming to a lot of people (the genesis of Python was in the CP4E project - where this was the aim). This resulted in a lot of bad patterns, inefficient code, badly written but popular libraries. Also, the indentation idiom and other restrictions resulted in a lot of convoluted APIs.There's also a lot of baggage from the pre multi-core CPU era (threading etc.).

I still think of it as a great glue language. If there are libraries that are fast and can run well, a good FFI or wrapper which Python can leverage will amplify the reach and usability of the library.

On the overall, a language that's older than the venerable Java which people are still using (and hence complaining about) speaks to its longevity. So, atleast by that definition, it is successful.