As we all know, automatic conversion for EE1 sites were promised but never delivered, and there are sites with very sizable image galleries which have yet to be upgraded because of it.
The baseline has likely been writing an entire new gallery solution using Pixel&Tonic Matrix, but this is a developer-level solution, due to the original Gallery's range of features.
EE's practical intents for designers and web-site owners are a very important part of its abilities, so how do we best serve this?
Chat with the folks at Solspace that will soon have the ability to use http://www.solspace.com/software/detail/importer/ to convert EE 1 gallery to EE 2. I can't remember the full details at the moment but there was a screenshot on twitter just a bit back showing EE 1 gallery to P&T Assets as an import selection could be other options but they are in a better position to share.
Edit: https://twitter.com/reedmaniac/status/263326523803709440
I think the best user-focused solution is actually changing galleries into entries in a dedicated Galleries channel and using Channel Images. You can do the transformation of existing data after your upgrade with some fairly simple SQL, and then going forward your editors would just add images into the Channel Images field in the channel entries.
The short answer is that there isn't a easy solution that will migrate all of the galleries features to EE2, without getting your hands a little dirty in code, other add-ons, or doing some manual migration by writing SQL queries.
Like you mentioned, the Gallery wasn't migrated to EE2, which was either an oversight when EE2 was built or just not a priority.
In the event you don't have a developer to manually migrate galleries for you using raw queries, it seems like the other option would be to familiarize yourself with Matrix or other EE2 gallery solutions, and manually migrate them by hand.
Unfortunately, this seems like choosing the lesser of two evils, but in my experience, those are the two options.
