Healing surges aren't a perfect solution. One difficulty is the "best doctor" problem.
Players have a limited supply of healing surges, which can only be replenished by taking an eight-hour "extended rest". Extended rests not only cost in-game time, they also reset your milestones and remove any excess action points you've accumulated.
During combat, players will take whatever healing they can manage. After combat, the rules allow players to use as many healing surges as they wish to heal up.
However, using an unbuffed healing surge is for suckers. The cleric is the best doctor. If you heal yourself, you're getting back a quarter of your hit points, rounded down. If you let the party cleric use a healing word, you're getting back the surge value, plus 1d6, plus the cleric's wisdom modifier. The cleric gets two of these "per encounter", which can be refreshed through a short (five minute) rest.
What was intended to be a quick way for teams to get back into fighting shape after a battle becomes an extended dice rolling session. No one wants to waste a valuable surge on an unbuffed heal, so now the cleric's rolling 1d6 for every surge for every player, and making notes as to how many groups of five minutes everyone rests to reset the healing words.
This appears to run counter to the design philosophy of 4th Edition. Post-encounter downtime is supposed to minimised under the new rules. One option is to restrict the use of these powers to honest-to-God encounters. The cleric is now inexplicably unable to call on his or her abilities when not threatened by monsters. Unimpressed players will begin attacking nearby rats and insects in an attempt to trigger a heal-enabling "encounter".
A better solution is to run a house rule. Establish that healing words used outside of combat consistently deliver a heal bonus equal to the cleric's wisdom modifier plus one. This isn't ideal, but it allows people to calculate their healing quickly without the cleric having to roll a storm of dice.
On the bright side, 4th Edition makes cure light wounds and cure serious wounds dailies. Few parties will take an extended rest just to reset those suckers when they're otherwise fine.
 House rules are good, but surely this issue arose during playtesting. Why wasn't it specifically addressed in the Player's Handbook? Or alternatively, is there something about the operation of encounter powers or heals that I'm not aware of which would circumvent this problem?