I think Knollspine is better than any creature that is just a beater. Including cool cards like Razia or Serra Avatar. In fact, the Dragon may replace Razia in my stack. I think his ability is far from great, but it's decent and he's a solid beater on top of it.
If a creature has both a bad ability and a bad body he doesn't cut it, unless it's better than the some of it parts or the ability is really freaking greater than it seems. I like hasty creatures, and razia has both haste and vigilance. Than again, she's legendary and has 3 toughness. And he is a dragon, and is on theme with Knollspine Invocation and Spinerock Knoll.
I'd put it right above Din of the Fireherd (which I dont think I really want to include. As much as it's nice to kill a land and a creature with one card, i don't know if that's good enough for a sorcery even with the 5/5 "bonus" creature which I couldn't care less about)
A 5/5 free token is really great. Generally, the medium sized creatures are the ones that win games. See Beast Attack and Urza's Factory. No one will spend a removal on him, because better creatures will come. Many people think he'll get swiped by their next mass removal, but usually there are players that will commit a bit to the board and won't let that WoG resolve. And 5 to the head each turn is a lot. Token have uses beyond just attacking. You can sacrifice him, or use him to pay convoke. And the token's art is hot.
And that is just the worst case. If you happen to control another red or black creature, or a black and red creature, it gets better.
I agree that Blue reflection is much weaker than all those draw spells that you have mentioned, but those are ones that are hotly contested when they are played. Tower of Fortunes is EXTREMEMLY hard to resolve (and often ends up hit by Desertion or otherwise stolen), Mindspring depends on how greedy you are with it, but often causes a counter war. Getting those cards off is not easy and you deserve to reap the better rewards from them if you do. Conversely, Thought Reflection seems like it might be safe to allow a player to have, and then you play a couple cantrips and really get ahead.
Thing is, it still doesn't do a lot on it's own. Even if it doesn't do much, it has the threat of doing so, for good and for bad. There are cards that do much more than him even he's used to his full potential. It is a great card, but because he requires you to draft draw spells or at least a few cantrips, for an effect that's achievable in a single piece already, he won't be a high pick. I think most players will draft it AFTER they have drafted their draw spell, and not before, so in the pick order he's right there.
