I think the reason why Tralee suffers in some people's minds (but not mine) is that there is such a different character to the nines. The front is vaguely TOC-like: much flatter, lacking the more impressive sea views and Ballybunion/Lahinch scale mounds. Wide open links. The back is more constrained, playing like Prestwick in terms of some quirky lack of options in places. But Prestwick is forgiven for this because it is Prestwick and it has been there longer than any of us. Tralee's back nine sins because it plays through the dunes, and takes advantage of the eye candy where it can. Some people can never forgive a course/architect for this (see Old Head)
Personally I think Tralee is a solid 8, maybe 8.5. It could be a 9 with a few minor changes. It'll never be a 10, but with all the work done on Waterville I still don't think it is a match for Tralee. It has a bit of a manufactured quality to it on some holes (especially on the front nine holes that were renovated) that I can't get away from. Yes, it does have its strategic standouts like the 16th (Liam's Ace) but it never hits its stride for me because everytime it strings together several nice holes it intersperses a weak one that really hurts it, this is a particular problem with the par 3s.
There are some who really dislike Tralee's par 3 12th as an example, but there is no denying it is one spectacular hole. Some dislike it since in some conditions could be said to provide NO options (I played it last in a 40 mph following wind) to put the ball on the green in regulation, but dismiss the fact it is well designed for this eventuality and provides places to safely miss and give a chance at an up and down.
Having played Waterville twice (pre and post renovation) the only thing that would have me back on my next trip is the beauty of the Ring of Kerry. Makes it a perfect destination if there are non golfers in your group. The only thing that'll keep me away from a return to Tralee would be if there just wasn't time since Ballybunion and Lahinch, as 10s, are must plays whenever one is anywhere near them, regardless of anything else. Hopefully next time I'm back I'll have time to play all three, and the wind will be howling and the rain staying away!