The important thing is why your application was refused. Typically a spousal application is refused for one of two reasons: they don't believe the relationship is "genuine" - in other words, you did not provide enough proof with the application supporting your relationship and they assume that you are only in it to get into Canada, but normally they will invite you to attend an interview first, before refusing for that reason. The second reason for refusal is that the applicant (or an accompanying family member) is medically or criminally inadmissible to Canada. Spousal applicants and their dependent family members are excessive medical demand exempt - except in cases where an illness poses a threat to Canadian public health and safety. So, in most cases, refusal of a spousal ap for inadmissibility is about a criminal conviction - sometimes one which the applicant felt was totally insignificant or a "mistake" made when young and stupid. When Immigration Canada gets involved, though, those things come back to bite.
So - again - everything depends on the reason for the refusal. If you simply didn't realize the need to provide supporting evidence of your "genuine" relationship, you may want to just start over again and be more prepared on a new application. If you did provide lots of proof, and you even had an interview, and they still didn't believe you were "genuine", an appeal would be the way to go - because in an appeal, humanitarian and compassionate discretion can be applied where a lack of solid evidence exists. If you are somehow criminally inadmissible to Canada, that's a bigger issue. The particulars of your case would have to be examined by someone qualified to make a recommendation in regards to whether or not you are at a point where you'd be eligible to apply for Rehabilitated status - and then file a new PR application; or if the situation was such that they might consent to allow an appeal on humanitarian and compassionate grounds. It's not a science - the particulars in such case would have to be carefully considered. My immediate advice - either way - would be this: have your wife fill out and submit the request for appeal. It does not lock her into that avenue - it simply preserves the option and gives the two of you time to consult with someone and decide how to move forward.
Again, for our purposes here, we really need to know what paragraph of the IRPA was cited in support of your refusal, and on what grounds. That will help us try to help you figure out how to move forward. Also, if you tell us which province your wife is in, we can tell which IAD office would handle her appeal and give you a general idea of how long to expect it would take. Having been through this myself, I feel your pain. But all is not lost. I disagree, to some extent (again, dependent on the reason for the refusal) with what you've been told about there not being much chance of success with an appeal. Most spousal appeals are, actually, allowed because of humanitarian and compassionate discretion. Again, it really depends on the reason for refusal. Feel free to PM me if you want your reason for refusal to remain private.