Just an addition: the lifestyle is variable, but in general, the heme/onc lifestyle is much better than that of some of the other medical subspecialties such as cardiology, critical care or even gastroenterology. In general. your patients are sicker, so you might have to take calls, but usually there is someone there to take care of them.
Reimbursement is as described. At present, it is one of the more competitve medicine fellowships (probably after cards, GI and AI, it's up there), but with some good research and good letters, its highly achievable. Most of the fellowship programs have also moved to a common offer date, which also favorable to aplicants.