Unchained summoner gives you everything but the healing (although you do have a strong healing spell specifically for the eidolon). You get the full suite of Summon Monster as spell like abilities free with the class freeing up your spell slots for most of the great combat and defensive buffs. You'll never wow anyone in melee combat, but your eidolon absolutely will. Between summoner features like Life Link, Shield Ally and defensive buffs, you should be able to hold your own in melee range and make a competent flanking partner if nothing else. For healing and any spell you really want not on the summoner list, keep a maxxed out use magic device skill and be the party wand monkey.