There are a lot of things I like about it:
- it's an open source project - open source projects should use open source software if available
- interesting workflows possible, but also what we are used to
- contributions processed per string rather then a lot of strings in one go - this is IMHO a current problem on AMOS, where it is possible to create contributions too large to be nice to process.
- I like the suggestions and comments-feature
- Using a secondary languages as an added source language. A lot of our translators speaking better French, Spanish or Russian then English will like that a lot! It's a frequently asked feature.
- It could do Moodlenet-translation if there is interest from that team to move to an open source translation interface
I couldn't find anything, apart from a lot of work to move and refactore things, that speaks against weblate.