It seems to me this is generally a bad idea for multiple obvious reasons, and more not-so-obvious reasons.
1. How can they keep track of all the pieces that might be stolen? Everyone knows how much value there is in LEGO, and anyone can simply pick up an interesting figure from an expensive set and resell it. They claim they check every set to make sure it's complete, but someone has probably already found a loophole. (A possible answer could be the fact that they must have an address to confront someone if suspected of reselling, but even then, you can gift sets to someone's house when they aren't there, pick it up, rinse and repeat. People are getting more creative with finding ways to make a few bucks, and for some that's through thievery.)
2. Who wants to RENT LEGOs? Most kids I know like building their own creations out of other sets to make their own creative vehicle or building (heck, I even do that). How are they going to keep the kids from not tearing up the set and mixing it in their own collection? Do the parents then have to buy the set from them? Do they have to spend hours picking out the pieces? Kids are messy and irresponsible, and the parents are sometimes the same. (They say you can buy the set from them at a discounted price, but how much of a discount and from what price? Original retail, or current retail?)
3. Only 1 at a time. I know that it makes it easier to keep track of, but what if you want to play with say, an X-Wing and a TIE Fighter, but can only rent one at a time? No answer to that except buying one, but that defeats the purpose of renting them, doesn't it? They suggest registering two accounts, but then you're paying TWICE as much to rent sets per month.
4. Renting. I don't know if it has changed, but there used to be 3 plans to choose from, Fan, for $15 (Get $25 sets and under), Super Fan (approx. $50 sets and under) fro $25, and Mega Fan (all sets) for $39. The only plan that is worth it to me is Mega Fan because you can get EVERY set, including the uber-awesome Death Star that retails for $400. I think most parents and kids would gladly pay 10% to build that set and play with it for a week or more! However, when it gets down to it, unless you live close to their shipping place, you are waiting on average 7-8 days for ONE set. For something like a small $20 City set, that is unacceptable. That means you can barely get 2-3 days of play for one set while waiting 8 for it to get there. If you've done the math, that's only 3, or if you're lucky 4 sets per month. THAT sucks.
5. Overall price. Since we're on the subject of Math, it doesn't seem like too much money at first, does it? $40 for a month of renting sets rather than $120 for sets all over your house, not bad. BUT, let's take a closer look. For those who thought that word problems were useless, I