I have Linux+ also (and I was teaching it last year).
Its a good entry level qualification aimed at those going for sys admin roles.
A *slight* critisism is that they've changed the format of it.
The 2004 objectives (which is due to be retired next month, october 2010) involved 1 exam and meant you were certified for life.
The new format is there are now 2 exams and it is relevant for a finite period.
Plus points for it are that if you now pass the 2009 objectives, you gain membership of LPI.
The bad news is that with the 2 exams, you are basically doubling the cost of certification (and I suspect the expiry on the qualifcation is due to the desire to get returning trade).
The single exam was £160 I believe and the two exams are £110 each AFAIK.
That said, I certainly believe it is worthwhile.