I recommend requesting an official interview or meeting at which the details of the job will be discussed as well as the salary range, benefits, etc. At that meeting, you should be sure to "lay it all out" -- the responsibilities, the expected workload, working hours, etc. ... as well as the total compensation package. Also, you should open discuss how the responsibilities, workload, etc. of your current compares and the compensation you receive for doing that job.
Do all of this in a friendly, courteous, and respectful way -- in a spirit of exploring the job offer, not of being argumentative or difficult. Once you and your boss get it all laid out, it should be pretty apparent to both of you simultaneously whether or not the offer is reasonable.
If it is not reasonable, give your boss a chance to correct it ... or to offer you some sort of deal that will make it palatable. If that doesn't happen, then decide whether or not the "experience" of the job will be worth taking it anyway. Sometimes a job comes with some intangible advantages that are worth a little sacrifice in other areas. Sometimes those advantages are that you learn a lot from the job that will be useful for your career in the future. Sometimes the advantage is that you valuable experience that will help you get a better job in the future. Sometimes, you simply will like the work better in the new job and it is worth taking a salary cut to be happy in yoru work.
If you have covered all the stuff I have listed above, your decision as to whether or not to take the job should be a lot clearer.