First, remember that substitution levels can be taken in whole or in part; you can take one of these substitutions and not the others, if you wish.
Dragonblood Sorcerer 1
Familiars are generally better than Draconic Heritage; only do that if there are particular feats that require it that you wanted to take. I don’t remember there being any that were particularly good, but maybe there’s something that interests you or whatever.
Dragonblood Sorcerer 4
The 4th-level substitution depends a lot on what spell it is. But at 4th level, you only have 2nd-level slots, so you’re talking about a 1st-level spell that you’re casting thrice per day. There are some great 1st-level spells but I cannot think of any that I’d want to cast three times a day, every day. Besides, you could always take that feat that allows you to split up your spell slots if you really wanted; you’d be able to trade a 2nd-level slot for two 1st-level slots, and then you’re not restricted to that particular spell.
But, do note the special rules for spell-like abilities, versus actual spells. Most importantly, they don’t have any components: no gestures, no chants, no materials, no foci, and no experience cost. If you can find a 1st-level spell that’s got an annoying gold or XP cost... that could be worth it. But as a 1st-level spell, that’s not exactly thrilling. The only thing I can think of is identify, and there are plenty of easier ways to get that (Artificer’s Monocle in Magic Item Compendium is my choice).
This ability gets a whole lot better if you can somehow delay Sorcerer 4 until after you have higher-level spells. Getting a free identify is OK; getting a free forcecage or legend lore or true seeing is rather cool. But I cannot think of too many ways to do that without losing spellcasting levels or getting DMGs thrown at you.
Dragonblood Sorcerer 7
You get one more 2nd-level spell than you otherwise would. On the other hand, you don’t get to choose, and your pre-selected spells are not so great. You probably wanted fly no matter what, and resist energy is pretty good, but bless is garbage, darkness is only OK, and charm and suggestion both suffer for being [Mind-Affecting] (which way too many things are immune to). I suggest a pass on this level.