The biggest drawback to the class is probably the fact it has few aoe skills, unlike the Champ and LM. You can do a lot of things(debuff, dps, cc) well, although maybe not the best. My burg can out dps my champ on 85 training-dummys, with the unseen set. My champ still uses a 2h and can't use merciful strikes but my burgs has limitations too. The t6 debuffing gamble is maybe the most crippling in the game and is automatic with Gambler's Strike. LM all around debuffs and CC are awesome but fire-lore has limitations on use, once per minute. Burg debuffs stack and can be used multiple times. Lack of group heals, except for FM, are one downside.
Burgs are also good at pvp with the gambler or QK line. They can be renown machines, stealthing up to creeps and picking them off one at a time. They're not bad at 1v1s either. I've got a LM and burg at 85 and I play my burg, not my LM. They're a lot of fun. Here's a video of Leafelyn at the School of Tham Mirdain.
Tedemir - 100 Champion, WM Historian(K/Weapons), Rk 12
Azuriael - 100 Lore-Master, WM Tinker(K/Jewelry), Rk 4