GameTap is very much worth it - as long as you don't want to run it on a 64-bit Windows. I have used it much less since upgrading, and it is one of the reasons I might switch back to 32-bit Windows. I can still play non-Windows arcade games on it, but it's not the same.
But, besides the 64-bit issue, it is a great deal.
Plus, like Steam or TotalGamingNetwork or other online delivery platforms, I can use my 1 Gametap subscription on my many computers, just not at the same time. (I think they have guest logins, but my s.o. has not used hers.)