My experience of watching these Blu-ray upgrade threads over the years are some people are adamant they can see no difference, whilst others are adamant they can see a difference. Personally I did, but I have to say in most cases, the differences were fairly subtle (though I did find the audio differences more pronounced). This was also several years ago and technology has inevitably moved on, so my experience is now definitely out of date.
With this in mind, I don't believe anyone can tell you with certainty whether to upgrade or not - the only way to know if it's worth the money for you or not is to take your old player with you and do a comparison with the new player, then make the decision based on your own experience and whether you believe any perceived differences are worth the extra cash.
I know others will disagree with this advice, so it's available to be taken or left as desired.