Hmm...they grow pretty darn fast when they are cared for properly. While I'll say that your tank doesn't offer much height, it is still adequate for housing a young iguana until it is approximately 1.5 yrs old. At that age, it will likely be around 3 ft long and you will definitely need to have more spacious housing ready for it.
On the issue of their temperment, I'd say its variable. My general advice is you're going to get out of it what you put into it. The more time and interaction you give your iguana as a juvenile, the more tractable it will be as an adult. Lord knows no one wants a 6 ft irritable iguana on their hands. However, keep in mind, that every iguana has a different personality and some just don't like to be handled as much as others.
I definitely suggest reading the Ultimate Iguana Manual