Having almost completed my MPA from Sciences Po and being a non-EU student with no French skills, here are my observations:
1. Sciences Po is highly regarded in France and to some extent across continental Europe. However, the absence of French language skills will hurt you when it comes to finding a job. If you're American for example, you're much better off going for a degree which has a better brand-name in the English speaking world. However, if you're an EU citizen and can speak a continental EU language, then things can change for the better.
2. The MPA's been an excellent academic and practical experience, the professors here are mostly practitioners as opposed to academics, which is wonderful. You will get new perspectives on things, this is the best part of being at Sciences Po. And your social life won't suffer due to French language too much!
3. Sciences Po Avenir is great for those who can speak some French, for the rest of us it is largely irrelevant. Finding jobs is entirely your own responsibility, which isn't great with the continuous workload of classes.
Hope thins helps in making a more informed decision.