Now that my son is a little over 3 and half, I figured he was ready for regular size Legos. The box says 4 years old, but he's big enough to handle them and hasn't eaten anything he shouldn't in years, so I figured it was safe. Plus, I really, really wanted to play with them myself. :-)
They have a big box of Legos at Fry's for what seems like a great deal: 700 pieces for $15, so I grabbed a box the other day (my birthday - it was his present...) and we've been playing with them since. Alex likes them well enough, but he likes it better when I make stuff for him. Which is fine, because they're so fun! It's really relaxing to snap the pieces together and create a little instant toy that immediately is used by Alex. I made him a little house for his Thomas trains just now, and he thought it was so cool. That's very satisfying.
I'm so going to have to resist buying 10,000 pieces online now - people auction off boxes and boxes of them for reasonable prices. It's so tempting!
Update: I just remembered I might have posted about this before... Turns out I've been waiting for this moment for a long time! :-D Hehehe!