I went last year - we did 3 nights in Havana, at a lovely hotel with only breakfast and Havana was perfectly safe to walk around, we ate and drank at several local bars and restaurants. We then went all inclusive to Varadero for 7 nights, I wasn't keen on this - it's not really my 'thing' the food was excellent for Cuba but poor compared to what you would get in Mexico or similar. Varadero was very safe to go out and eat and drink. The main problem I would forsee, is that food in restaurants is very hit and miss, not so much in quantity but in actual ingredients due to food shortages. So, you might order fish, with potatoes and veg and you may get different fish, maybe with different veg than you were expecting.
From a cost effective point of view, it may be better to do a package like we did and just go out to eat and drink each night, or every other night.