He looks to be a decent little horse. He is built pretty good from what I can see. I like that his bone is sturdy. Yes he does look like a little chunk, but it looks like a lot of bone is also hiding under that chub. I'd go take a look at him in a heartbeat.
For what you want, I think he's at the least worth going to see. He looks like a very nice boy, and there's nothing I see that's really wrong with him- I think he is, overall, a very good looking horse!
Agree with everyone, this one looks really good, lots of potential. Substantial bone to hold up the stocky frame which is great. I want to hug him, he looks like a love bunny but maybe that's just the whole 'fat cute' thing! Go see him!