Considering we don't know very many feats or powers, it's hard to evaluate the multiclassing system. First of all, we can't compare the costs. Is 4 feats a lot? Well, maybe. It depends on what other feats the character is going want - some characters might not have any trouble operating with fewer feats. Other feat abilities may diminish much of the need for multiclassing anyway - if a character can pick up good weapons and/or armor and get them to work effectively via feats, then those abilities cover much of the traditional need for fighter based multiclassing. Similarly, if rituals require a ritual casting feat and then training in an appropriate skill, that offers another avenue for gaining atypical abilities without using power swapping (of course, the first mc feat probably provides one of the skills needed to use a ritual). Some characters will probably be able to get they want for 2 feats to pick up a utility or encounter power too - having 1 big cross class trick to pull every encounter. If 4 feats is too expensive, then 2 might not be so bad.
Similarly, it's hard to say what exactly the character is gaining. However, some of the wizard encounter powers at level 13 seem pretty sweet for a fighter or rogue. Prismatic Burst -> Blinding until the end of your turn -> Sneak Attack? Or how about Frostburn on a fighter? Slam a group of enemies with it, then move up to the edge of the area. Now the targets are in difficult terrain for movement penalties, will take ongoing damage, AND will be pinned in place by the fighter's opp attack features. One of the powers even used Wisdom instead of INT, reducing MAD.
Since some kind of recharge mechanism has been mentioned for powers, we might want to see that too. If a multiclassed character can keep recovering their off class power, then they'll be using more of their secondary class without necessarily investing more into it.
EDIT: Also, I can't be the only one who has found the table summaries of feats to often be useless or misleading in previous WotC books. While I'd like to hope that things have changed, being suspicious of the summarized feats has paid off in the past. It might be more useful to have the actual text of the feats.