we were pleasantly surprised at the transition from crib to bed for both of our girls...for my littlest one, we put a safety knob on the inside of the door so she couldnt get out and then we close the door every night...the other one, never got out of bed! she went from a crib to a pack -n-play right to a queen size bed...she did not like the toddler bed, but had a good transition as well.
one tip...they are not in a toddler bed for too long. unless you have the money, try to get a nice used one or a cheaper one at walmart, kmart etc. you may want to invest in a nice twin bed as they will use that for years!