The Favored Soul plays pretty well as a "melee cleric", if you have chosen a deity with a decent melee weapon, of course.
With the weapon feats and no domain powers/turn undead ability (no Divine Might therefore, which would fit very well, unfortunately) its a bit more warrior-like even.
As for stats, that's one of the biggest downsides of the Favored Soul. They need many good stats!
Str for melee is obvious.
Dex can be lower, just like with a cleric, but lacking the heaviest armors, they need it a bit more. Tho, they can still use mithril full plates as they count as medium armor.
Con is a no-brainer for every char, that gets into combat.
Int is not needed that much, but it's still very nice to have for the Combat Expertise chain or some skills.
Wis is needed for spell DC. If you go more into the warrior/buff spells direction, you won't need it that much, but if you want to use offensive spells, it's a key ability as well.
Cha is needed for spell access and bonus spells, it's very important to have a high enough charisma to be at least able to cast the spells!
So, Str, Con and Cha are most important, followed by Dex, Int and Wis.
Concerning the power level, I think they are pretty much even with the cleric. The lack of turn undead and domains is a big downside, while spontaneous casting is a big advantage, but they also need two stats for spellcasting and another two for fighting, which lessens this advantage quite a bit, unless your stats are really good. And while they know more spells than sorcerers, so do clerics compared to wizards, since they know all spells. They still get the higher levels one level later and they also gain less spells per day as the sorcerer does over the wizard, since they have the same and clerics have more than wizards. The good Reflex save and Energy Resistances are nice, but hardly major abilities.
Bye
Thanee
P.S. @uzagi: FS has no heavy armor proficiency.