I only really have two gripes with HARP, but the second one really bothers me:
1) As others have pointed out, the concept of levels and DPs tied to stats. I guess that could count as two.
2) The lack of decent, modern, GM and character creation software. I find it appalling that it's nearly 2010 and ICE has no solution for any of its product lines. The various spreadsheets and interactive PDFs for character creation are adequate, but I've found them slow and clunky. Plus, I've been unable to get any of my players to embrace these. With work and family I don't have the time any more to create dozens of NPCs, so I either just wing it or re-use the same tired NPCs year after year. I should be able to choose the parameters I require (race, class, level, particular skills or spells, whatever) and after a few moments of number crunching an NPC is spit out. With a little tweaking you can do the same for PCs. And a combat tracker would be a god-send! I pick my NPCs or monsters, select which PCs are in the fight (because the app already has their stats, abilities, and skills), and just enter rolls each round. Cover, movement, and other modifiers can be changed easily, and bleeding, stuns, penalties, and the like are kept track of for me. Did I mention it should be intuitive? I've looked at the various virtual tabletop solutions, but they seem to be very user unfriendly.
Wireless is ubiquitous wherever I game, so I'd prefer an online solution. That way my players could update their characters at their leisure and we don't have to worry about losing or remembering a sheet. If it were a "real" application I'd prefer a cross-platform app, but I can run Windows on my Mac so I'd be happy with even a Windows-only solution. I'd gladly pay a monthly subscription for online, or a reasonable amount ($20-$50) for a standalone application. I've often attempted (or planned to attempt) to create such solutions, but my programming skills aren't up to the task. I'm the only one in my gaming group with a shred of computer skills, and my experience is limited to Unix shell scripting and web development (PHP, Perl, Javascript). It's a huge project for one person, and I'd love to help out on such a project, but unless it's coded in something I know I'd be left with just telling people what I think is best. And the world is full of enough people that are more than willing to offer up their opinion.
Other than those, I love HARP. I do miss RM from time to time, though I like how HARP took many of the strengths of RM and streamlined a lot of the rest. I started with that not-licensed-anymore-RPG in the mid '80s, switched to RM2 in the early '90s, and then to RMFRP for a couple of years before HARP came out. Keep up the great work!
Happy Christmas-Hanukkah-Kwanzaa-Winter Solstice-other holiday to all!