Do you mean the Blade CX2? As in this one:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=002&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=120125014113&rd=1&rd=1The only downside I can see is the battery. As I'm finishing up my graphic design degree I work part time at Batteries Plus to pay the bills. After a couple years there I've seen almost every type of battery you can even imagine. I've had a few fellows stop in the store looking for replacement batteries for a similar helicopter. A Lithium Polymer battery, which yours uses. You'll find these batteries a lot in cell phones and electronics where weight is key because Li-Poly has the best weight to power ratio available for mass production. However, there are some downsides to it. It offers a few less cycles per life of the battery than lithium ion (around 300-500 on the average) so expect a relative life span of 2-3 years on the average. Remember no matter how little you use the battery time is also a factor as the chemicals inside break down even after nominal use. So don't expect to use it a dozen times and come 4-5 years later expect it to work at 98%.
Lithium polymer, like most battery chemistries can be explosive. It can be considered more prone to exploding (still a very smal percentage, remember they are legal to the public) than lithium ion, nimh, and nicd. I've talked to a few RC car racers that say they've witnessed RC car crashes which involved a lithium polymer battery exploding. I have not witnessed such an event but it can happen if a impact ruptures the battery.
The other main point I want to make is battery availability. Most of these manufacturers make a unique battery pack for their product and few if any aftermarket companies work to copy the design. If you plan on owning this for several years, make sure the company has spare batteries and they will be readily available in the future.
I've tried to aid customers in finding a Li-Poly battery for helicopters before but could not find an exact match. Either the battery was too big or too small (would not allow enough flight time). Also the larger/smaller battery throws the balanced weight off on the copter.