Finally, a post I can contribute to in /r/askhistorians! I have a few books on the subject, none at hand right now so I'll try to give a quick summary if I can and hopefully that will be enough until either someone more knowledgable than I posts or I can get my hands on those books.

Ebert, politically, was viewed in a mostly positive light and as a competent politician, much of the blame for the later lackings of the Weimar Republic tend to be blamed more on Hindenburg for being ineffective. This is likely from both his political efficacy, but also the failings of the leaders who followed him, Hindenburg and Hitler, who can somewhat make anyone look better in a way. Directly, much of what he did strengthened interwar Germany, and little he did would have made it evident the Weimar Republic would collapse. Much of the blame for this rests more on Hindenburg and his government. Although, his use of the infamous article 48 of the Weimar constitution could be seen as paving the way for even greater presidential powers that would be utilized later to solidify the rule of Hitler and the NSDAP.

Most of this information I got from Peukert's The Weimar Republic: the Crisis of Classical Modernity and from Eberhard Kolb's The Weimar Republic.